An Attention Grabbing Dragonfly: Swamp Darners Catch More Than Prey
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There are themes that repeat in our visits and conversations together that reinforce the wonder and amazement found in the fields, forests, creeks, and ponds of Harmony Hill. Part of us sharing these recurring themes is the shear giddiness we find in the gifts of Mother Nature. But a bigger portion of it is that we want you to seek the same joy in the species, the connections, and the beauty found around you, wherever you might be. Your very own backyard, a neighborhood or state park, or any public greenspace can be a Harmony Hill where you uncover the mysteries of delicate spring wildflowers, melodic bird songs, the process of insect metamorphosis, or the intricacies of the web of life.
Just last week, we talked about a species of butterfly, taking to the air in beautiful flight. You’ve likely noticed we can talk for lengthy periods about birds. And if you stay with us as we continue these regular visits, we’re going to spotlight bats, the only mammals capable of sustained, powered flight. There is no doubt whatsoever that we are enthralled by all things with wings.
Today, we’d like to talk about another winged species; but not one with the immediately recognized loveliness of a butterfly or feathered features of a bird.
Any amount of time on the creekbanks or around the edges of the pond here in the spring and summer includes sharing the space with the darting, dashing, and diving of dragonflies. We are blessed with quite a variety of species, with colors and patterns that cover nearly every shade found in rainbows that arch across the sky following an afternoon summer shower. We’ll be talking about more species down the road, but one of the largest dragonflies we have at Harmony Hill is taking to the skies and their impressive size catches our attention. And we think they’ll fascinate you just as much as they do us.
Most of the dragonflies we see during our time outside are a couple of inches in length, with about the same size wingspan. But there is a much bigger species that is regularly found in open areas near the waters of Harmony Hill. There is a fairly common species that can reach around 4” in length, with a wingspan that can exceed that measurement and a body that is strong and heavy in appearance. The Swamp Darner (Epiaeschna heros) will grab your attention if it ever zooms near you, if for no other reason by its size!
Even its scientific name alludes to the how much bigger it is than most dragonflies. Epiaeschna means “in addition to” Aeschna, which is itself a genus containing many species of dragonflies. (As an aside, Aeschna means unattractive or ugly… and we totally disagree with any assessment that dragonflies are ugly!) The species name of “hero” is a word we are all familiar with, as it means a protector and demi-god. For the Swamp Darner, it is another nod to just how big individuals are, as any dragonfly this large might have the blood of some mythological deity.
Dragonflies, along with their close relatives, the Damselflies, are in the Order Odonata, meaning “jaw toothed”. True to that name, they used their strong mouths to devour prey at all stages of their lives. (And, no, they don’t really have teeth. But, if you’ve ever gotten an up-close look at their mouths, you know just how big they are in proportion to the rest of their faces, and you get an idea of just how those strong jaws can chew on the bodies of prey.)
Remember the stages of metamorphosis we learned in elementary school science? How some species of insects undergo various types of metamorphosis, with three types of metamorphosis being recognized by scientists. Depending upon the life stages throughout the process, an insect may be seen as undergoing Ametabolous (little to no metamorphosis), Hemimetabolous (gradual or simple metamorphosis), or Holometabolous (complete metamorphosis) types of metamorphosis. Most of this is revisiting things we all learned in elementary, middle, and high school, and even reviewed in the early days of Biology 101 in college. But if you’d like to take some time to focus more on metamorphosis, we can make that the topic of a future visit. No matter how many times we talk about it, it still amazes us that species change quite drastically from one stage of life to another!
Like other members of the Odonata order, Swamp Darners undergo Hemimetabolous, or gradual, metamorphosis. In that lifespan, an individual Swamp Darner will pass through an egg stage, a nymph (actually a Naiad) stage, and an adult stage. Most darners in our area will have more than one generation each year and Swamp Darners are no exception. Depending upon the weather, it may not be unusual to have up to three generations of Swamp Darners in a year at Harmony Hill.
In the spring, the naiad stage Swamp Darners in the waters of Harmony Hill emerge and molt into their adult stages. The time in which they do this varies on the calendar, but it coincides when springtime low temperatures regularly stay above about 50F degrees. The new adults take to the air with a sense of urgency, as they must reproduce within the limits of an adult stage that will only last between 4 - 8 weeks. With intense pressure from predators ranging from birds and fish to frogs and bats, their lives may very well be even shorter than that!
Once the adults reproduce, the females quickly lay eggs, with protective males actively watching over their territories. The second generation is underway, as the next egg and naiad stages might only last days or weeks. Unlike some species whose females lay eggs directly in water, Swamp Darner females lay their eggs near the water, in damp locations. Females have been observed laying eggs in the mud, in the cervices of fallen trees near the water or, in what may surprise many, inside the top layer of plant tissue or tree bark near water. You see, female Swamp Darners have ovipositors that are perfectly capable of slicing into and penetrating some plant material in order to lay their eggs. Eggs laid in this fashion usually hatch in the dampness of the environment in which they are laid. Some eggs may lay dormant until rehydrated by rains or rising water levels. Once hatched, the naiads will make their way into the water to complete this stage.
Once those naiads are ready to crawl out and molt into the second adult Swamp Darners of the year, the cycle of finding a mate and preparing for the third generation begins.
Let’s take a second and talk about this time as an adult. We just mentioned that adult male Swamp Darners, like many other species of dragonflies, establish, and defend a territory. While some dragonfly males patrol their territory, Swamp Darner males prefer to perch and watch over their area. An insect with a brain so small and simple in appearance that many would not recognize it as an organ capable of any complex neurological activity is, in fact, capable of far more than most would ever expect! Swamp Darners are capable of filtering out motion to focus on visual cues for potential prey and potential threats from predators and other members of their own species. Males are capable of setting up a defined territory, with appropriate habitat for attracting females for laying eggs and finding enough prey to capture. And both males and females are capable of navigating during a migration before setting the third generation into motion!
Now is the time when we pause and encourage you to think about what we just said! An insect with a head that is roughly the size of an adult human pinky fingernail can navigate, behave territorially, and can track targets that equate to us following a baseball traveling around 125 miles per hour! (Sometimes all at the same time!)
The third generation of naiads for the year will overwinter in the waters here, actively hunting for most of the days, weeks, and cooler months of winter.
At all periods of its nymph and adult stages, Swamp Darners are veracious hunters that will capture and devour whatever prey items it can chew and eat. As a naiad, that is usually found in the form of other aquatic invertebrates swimming and crawling in the waters around it. As an adult, that is any invertebrate it can catch on the wing and nibble away on. Their diet includes mosquitoes, flies, yellowjackets, horseflies, other dragonflies (including other Swamp Darners), and even the occasional spider, beetle, or ant.
Well now… we told you we are fascinated by all things with wings and this visit has certainly found us covering all sorts of topics as we discuss a dragonfly that always catches our attention! Large, beautiful, and, as it turns out, smarter than most people give them credit for, the Swamp Darner is more than a flying tank of an insect. It is a multigenerational resident each year at Harmony Hill, and it is an important part of our natural management of mosquitoes and other flying pests. They may not have the stylish, scaly wings of a butterfly and they may not sing the lovely songs of birds, but they are absolutely a valued and revered flier in the airspace in and around Harmony Hill.
Dogbane Tiger Moth: A Story in Shrewd Survival
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During so many of our visits, we make a point to talk about the beauty of nature and of just how striking so many species are to the eye. There is so much happiness found in looking out over the rolling hills of the piedmont and seeing the leaves change each fall. There are birds with feathers that shine in the sunlight that make you gasp, like when a Prothonotary Warbler, the jewel of the swamp, perches in front of you. And there are flowers so lovely, like those found on Tulip Poplar, that make you smile involuntarily. Nature is beautiful! And we are her apostles, proclaiming the stunning splendor right in your backyard.
But there is another side to the gorgeous grandeur found around each corner of the woods and the fields. There is a constant struggle of survival going on each and every second of each and every day. A battle of life and death, quite literally, is always happening; even as we sit in the quiet and the elegance of what we view as a peaceful moment in nature. Though we may stand in the dappled sunlight of a relaxing morning, predators seek to capture prey, plants conduct chemical warfare to prevent competition, and other species find ways to outsmart their would-be attackers. Whether by hiding, the use of camouflage, or mimicry, some species have found the best ways to lower the risks of being eaten are by fooling a potential predator. Let’s look at a species you may not be familiar with that uses a couple of methods to outwit hunters, one method that may just surprise you!
Sitting on the ground, in the wide open of a field, a cottony white moth with an ochre wash on its head and leading edge of its wings, is perched on the fallen needles of a Loblolly Pine. Sticking out like a sore thumb, even a seasoned naturalist would wonder if it had a death wish. Sure, the small amount of yellow-brown coloration on its forewing provides some means to blend into the scattered pine straw. But with so much of this moth being white, it can be easily spotted. (As seen in the accompanying photos with this Walk in the Wood.)
The Delicate Cycnia Moth (Cycnia tenera), or Dogbane Tiger Moth, doesn’t particularly worry about blending in or shying away into a hiding spot. Evolution has given this species two adaptations to use in its fight against predation.
Without the effective camouflage we’ve seen exhibited by some of the other species we’ve focused on, it would seem the Dogbane Tiger Moth would be the proverbial “sitting duck” as it loafs out in plain sight. And this moth doesn’t mimic another lepidopteran in order to borrow safety by being a lookalike.
What does it know that we don’t?
What tricks does the Dogbane Tiger Moth have up its sleeve to be able to lower its concern over being eaten?
For the answers to these questions, let’s begin by looking at the diet of the larval form of Cycnia tenera. Now, as naturalists, we all know that caterpillars of butterflies and moths that are capable of ingesting poisonous plants can build levels of the plants toxins in their systems, then use those toxins to become anything from unpalatable to downright deadly if eaten. We can look to the very familiar Monarch Butterfly (Danaus plexippus) and the way it utilizes the toxins found in milkweed plants (Asclepius sp.) to be both distasteful and mildly poisonous to predators. As it turns out, the Dogbane Tiger Moth uses the same approach and, on occasion, the same host plants as Monarch Butterflies.
The primary host plant for Cycnia tenera caterpillars at Harmony Hill is Dogbane (Apocynum cannabinum), a highly poisonous plant with a reputation for being so toxic, the common and scientific names tell of its ability to keep dogs away. The genus name of Apocynum can be roughly translated to “away with dogs”. In fact, civilizations have used the plant to poison animals, including wild dogs, in some way for centuries. And the species name of cannabinum is a reference to the plant being used, much like hemp plants, to make fibers and threads by Native American tribes, like hemp plants. Indeed, one of the common names for Dogbane is Hemp Dogbane; another nod to the way Dogbane can be used like hemp to make fibers.
The toxins in Dogbane effect the heart and are in the family of chemicals known as cardiac glycosides. However, the larvae of Dogbane Tiger Moth are unaffected and have evolved the ability to build up the levels of the glycosides as they eat the plant and grow. Those toxins carry over to the adult form of the moth we see in this Walk in the Wood visit, causing any predator that makes the poor decision to eat it to quickly spit it out or face an unpleasant reaction.
As a side note, it is not out of the question for Dogbane Tiger Moth caterpillars to feed on milkweed plants, like Monarch Butterflies. It was even once believed that Monarch caterpillars fed on Dogbane plants.
Being mostly active at night, the primary predator of Cycnia tenera are various bat species. Bats have learned to not eat Dogbane Tiger Moths through coevolution, with previous generations of bats finding out the hard way to not make a meal of the moth. But that is not where the story ends; nor is it the only way this moth has figured out to outsmart predators.
Bats hunt by echolocation. They use a series of vocalizations to hunt, communicate, and understand their surroundings. There are species of bats with a surprisingly large repertoire of vocalizations for a variety of situations besides just seeking out food on the wing. Well, Dogbane Tiger Moths have evolved to emit ultrasonic clicks that may serve as both a warning to bats to not even think about grabbing them out of the air and to also confuse their hunting vocalizations.
You read that right! This little white and yellow moth uses a type of radar jamming in the battle of survival against the only mammals capable of true flight! While we know the moth uses these clicks to deter bats from capturing them, we don’t exactly know if it is as a warning to not eat the poisonous bat or to disrupt the signal interpretation abilities of bats. It could very well be both! If you will recall, one of the things we have mentioned repeatedly is that things in nature rarely ever have one purpose. Either way, it sends out ultrasonic clicks to effectively remove themselves from the dinner menu of bats. And it does this when it detects bats approaching that have switched to clicks to hone in on a target! That, fellow naturalists, is incredibly fascinating!
A simple observation of a small moth has led us down the path of discovering how some species not only survive, but actively deter predation. A small moth that not only uses poison to prevent itself from being eaten, but also works to beat bats at their own echolocation game! And another example of just how special moments in nature can be without leaving your own yard! Oh, there are some astoundingly beautiful faraway places; but there are mind-blowing stories and amazing discoveries to be found mere steps away from your front doors. Now, get out there and find them!
Summertime Blues
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This time of year, our attention is pulled upwards toward the sky. The crystal blue skies of spring are a gorgeous backdrop for the bright greens of the new leaves on the trees. Birds flit around above us and sing from treetops, causing us to walk with our eyes scanning high. Trees like Tulip Poplar have bright and beautiful flowers blooming, as Crossvine and Trumpet Creeper add their blossoms to the upper levels of the forest. With all this activity above our heads, it can be easy to miss things at our feet. But this spring morning we are grateful we were scanning the ground as we made our way out of the tree line.
As we stepped into an opening, we happened to notice a small butterfly shape sitting atop a dew-covered blade of grass. The sun was shining in our face, and we could only see the backlit silhouette of what was obviously a diminutive butterfly. Careful not to frighten it, we slowly approached for a better look. Taking careful, soft steps, we circled around to put the sun at our backs and get a little closer. As soon as we saw the first hints of color, we knew which species we were looking at and it brought a smile to our face.
As with birds, flowers, trees, and even snakes, we look for a couple of quick and easy to spot field markers to help us identify butterflies. Some are simple, such as Eastern Tiger Swallowtail. Some are a little more difficult, such as the black swallowtails with purple and blue. It may take a few seconds of looking to know for sure, as opposed to knowing instantaneously. We’d like to share how we identified this butterfly, to help you when you’re in the field and encounter it. And we’d also like to share a little about where this lovely little butterfly fits into the overall Harmony Hill story.
One of the smaller butterflies at Harmony Hill, the Eastern Tailed-Blue (Cupido comyntas) looks a lot like their common name implies. When we say, “small”, we mean small; coming in at right around one inch in wingspan! They are blue above and have tiny tails that extend from both hindwings. That tail is one of the immediate identifying features of this species and one that we encourage you to focus on. There are a couple of other butterflies that look similar to the Eastern Tailed-Blue and, if you’re not careful, it wouldn’t be difficult to mistaken or misidentify them.
True to their names, male Eastern Tailed-Blues are blue when viewed overhead. However, females are predominately brown and can be fairly nondescript in appearance. Often informally lumped into “blues” with a few other species of small blue butterflies that look somewhat alike, this species is the only one in our area with tails. Formally, they are lumped into the Lycaenidae family and the Polyommatinae subfamily. But isn’t it easier for us to just call them “blues”? Though they may look like Spring Azures, Summer Azures, and Silvery Blues, the tails are one of two easy ways to separate Eastern Tailed-Blues from the other “blues”.
Two orange spots on the hindwings, often appearing as orange chevrons on the underside of the hindwings, are the other field marker to look for. As with the tails, none of the other “blues” possess such a physical trait. Their size, shape, behavior, and even overall color might give us pause, but focusing on the presence or absence of miniature tails and orange chevrons allows us to determine the identity of this species.
Also, be sure to look at the posture butterflies take when at rest. Some will sit with wings wide open, while others will rest with their wings clasped shut over their bodies. Eastern Tailed-Blues very often sit with their wings partially open, making identification much simpler. On this morning, the butterfly we observed rested with its wings closed; perhaps due to it being early in the day and the sun still very low on the horizon.
To warm themselves, some butterflies will open their wings in the rays of the sun. Gathering as much solar warmth and energy as they can, the increase in surface area is an efficient way to also increase their body temperatures.
How high or low they fly may also be a good clue to assist in identification. When it comes to Eastern Tailed-Blues, they are low fliers. Seldom getting above five to six feet, this species overwhelmingly prefers to cruise just a couple feet above the ground and the vegetation.
As we’ve discussed in our previous conversations about butterflies and moths, in order to have adult butterflies, you most often need to have larvae nearby. And as we know from talking about caterpillars, you need to have host plants for the adults to lay eggs on and hatch the larvae to munch upon. So, what host plants do we have at Harmony Hill that attract the presence of Eastern Tailed-Blues?
The top two host plants for this species are clovers; White Clover (Trifolium repens) and Red Clover (Trifolium pratense). Like so much of the southeast, or the entire United States for that matter, Harmony Hill has more than its fair share of nonnative White Clover. There aren’t many open areas that don’t have at least a few clover plants growing, meaning it is almost a forgone conclusion that we should have Eastern Tailed-Blues flying onsite. Upon seeing the male Eastern Tailed-Blue we observed for this week’s visit, we didn’t have to look too far to find deep green clover leaves spreading thickly in an opening. We took a few minutes to inspect the plants for eggs, but did not find any. During our walks, we will be certain to pay close attention, particularly if we see any females flying around.
Besides the two clovers species, other host plants for Eastern Tailed-Blues are also in the Fabaceae, or Legume, family. Members of the Lespedeza genus are host plants, and we have a couple species found over much of the property. Some of the vetch and pea plants, like Cow Vetch (Vicia cracca) and Eastern Milkpea (Galactia volubilis), are also known to host Cupido comyntas larvae. Though we haven’t documented female Eastern Tailed-Blues ovipositing on any specific plants, eggs on plants, or even yet observed caterpillars feeding on foliage, the abundance of clover and lespedeza here leads us to believe it to be the main host plant.
For the most part, the “blues” tend to have somewhat short flights. But Eastern Tailed-Blues are a bit of an exception, with a flight that lasts from March to October here at Harmony Hill. Compare that to their relative, the Spring Azure (Celastrina ladon), whose flight lasts from March to May. However, most adult “blues”, such as Summer Azure (Celastrina neglaecta), have a life measured in days. There is a lot to accomplish in that short life, such as reproducing and laying eggs. But they seem to do a fine job of doing just that, as we see a good number of each species each spring and summer in the meadows and fields of Harmony Hill.
The next gorgeous spring or summer morning you’re out for a walk in nature and you see a little one inch butterfly flying low to the ground, take a look to see if it is blue on top and gray on the underside. Chances are, it will be and, if it is, go straight into searching the hindwing for tiny tails and orange chevrons. You may very well be in the presence of an Eastern Tailed-Blue and a reminder to always look down, even as Mother Nature beckons your attention upwards to birds and leaves. Slowing down and looking all around you will reveal things often overlooked, and it will bring you more peace and joy with all you see.
Sculptured Pine Borer
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Have you ever walked along the edge of a field, through the woods, or even looked up at the night sky and wished you could capture the beauty you saw before you? There are artists who have been able to take a scene and perfectly present it, sometimes in their own way, that causes us to stare at their work. Whether it’s with a camera, as Ansel Adams so skillfully used, or with a brush, as masters like Matisse put their own interpretation on trees and hillsides, we have always been drawn to the use of light, shadow, colors, and scale to capture nature.
Yet, as much as we admire the talents displayed by these and other artists, nothing can ever compete with Mother Nature when it comes to jaw-dropping and awe-inspiring artistry. During this visit, we’d like to discuss a species that looks as though it would be as at home on the canvas of a Van Gogh painting as it is in a pine forest at Harmony Hill. Even its name points directly to the fact that it looks like a work of art!
True to its name, the Sculptured Pine Borer (Chalcophora virginiensis) proves Mother Nature to be a sculpture and painter. And it looks every bit as though it was designed by loosely swirling and blending paints on a palette, while keeping the insect cryptically colored and hidden in nature. That camouflage is perfect for hiding on the bark of a pine tree, a rock on the ground, or even the charcoal of a recently burned area of the forest. In the right light, it is even possible to see metallic glimmerings on the head, thorax, and elytra of this beetle.
With a name like Sculptured Pine Borer, we know you are wondering if this species is one of THOSE pine beetles! You know, the bad beetles that weaken and even destroy healthy stands of pine trees. Rest easy. This species only shows up on the landscape when trees are quite stressed and most often, when trees are already dead and dying. The Sculptured Pine Borer does not initiate damage or attack healthy trees. Adult beetles don’t cause damage at all, aside from munching on a few pine needles. In one of our photos this week, you’ll notice the remnants of pine needles around the mouth of this adult, meaning it did not wipe its mouth before visiting with us!
It has been our experience to only find them in places where dead and dying wood is present. And sure enough, it is an area exactly like that where we found this individual. As we were surveying a stand of Loblolly Pines that had been recently thinned, we walked over some downed course woody debris and stepped over some stumps of harvested trees. Though the woods were quite clean after a thinning, there were still some limbs that had broken off trees that were removed. It is that dead wood that no doubt attracted the Sculptured Pine Borer we discovered. The decaying of this wood in the healthy pine stand will continue and eventually the beetle will lose a reason to be in this specific location.
But we must remember adult beetles reproduce and make a new generation; grubs that do, in fact, eat the wood of trees. Again, it is important to remember that the adult Sculptured Pine Borers lay their eggs on trees that are dead, dying, or are stressed to that point. They seek out crevices in the bark of pine trees or even wounds or cracks in the tree itself to lay their eggs in.
These grubs are interesting to see in their own right. They have a flattened head that makes them resemble a small hammerhead worm! As they bore into the wood of dead and dying trees, they chew tunnels and crawl through the interior of the trunk and branches. Because of their flattened heads, the tunnels are wider than they are tall; giving the tunnels a shape much like a tiny sideways football.
If you ever split open dead or dying pine wood and see the channels dug by the larvae of Sculptured Pine Borer, you can even observe the growth of the larvae! As the larvae grow and they get bigger, so do the tunnels! If you have a piece of wood with a long enough zig zagging of channels of a Sculptured Pine Borer larva, you can observe the story of the lifespan of the grub by tracing the small tunnels to the wider tunnels!
Eventually, the grubs will chew their way out of the tree just as they become adults. Just as with their feeding channels, look for that oval, sideways football shape in the exit hole!
The question some of you may have might be, “Are we concerned about having this species in the forests of Harmony Hill?” The answer is, “No”. Considering we observed this in a part of the forest where we just had a logging crew do a thinning operation to increase the spacing and health of the trees, a place where we have down course woody debris on the ground and stumps of trees that were removed, we are not worried. This is precisely the sort of habitat we would expect to see Sculptured Pine Borers.
It is something; however, that we will keep watch for, should we experience a severe drought or other situation that could put extreme stress on the pines in those stands. We’ve had pretty good rainfall thus far this year; but, as anyone around here knows, that is something that can quickly change.
In the meantime, we will take a little time to admire the chiseling and brushwork of Mother Nature found on this beetle. The wavy strokes of an unparalleled artist showing her mastery of hues and color matching, hints of metallics, and making a gorgeous beetle that can disappear atop the granite outcrops and pine barks of Harmony Hill.
Before we close out this visit, let’s look at that name. We’ve all been able to appreciate the appropriateness of the common name, Sculptured Pine Borer. But what of the scientific name, Chalcophora virginiensis? Well, the genus name of Chalcophora means bearer of copper and is a direct reference to the metallic iridescence seen on this species in the right light. The species name is an easy one to interpret and is a nod to where this species was first collected and described, Virginia.
A very quick sidenote… A closely related species, Chalcophora georgiana, looks a whole lot like Chalcophora virginiensis. The Southern Sculptured Pine Borer often has a much more pronounced coppery tone on its exoskeleton, while the Sculptured Pine Borer tends to have an overall charcoal coloration dominated by blacks and grays. Though there are variations in the patterns and colors of both species, we feel confident in the identification of this individual, as there was a complete lack of copper and an abundance of gray and black.
Spring On the Wing: Mourning Cloaks Are Flying Again
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The arrival of spring at Harmony Hill is a complicated matter. Not that the added chores and activities around the garden and pastures make things confusing, as that actually gives clarity to the days here. No, it is that Mother Nature in our region doesn’t necessarily follow the calendar to begin her awakening from the winter slumber. Just a look at the weather and temperatures this past month and it is easy to understand why there are leaf buds popping out everywhere we look. Bluebirds have already begun inspecting the nest boxes and the daily concert of frogs along the creek and the edges of the pond are getting louder each morning.
One of the surest signs that winter’s grip on the landscape is breaking can be seen flitting in the warm sun; a glint of contrasting dark and light, of iridescence and matte colors, of life lifting from the lifeless cold of the short days of the previous season. On beautifully graceful wings, sometimes worn and tattered from a lifespan far longer than any of its relatives, the Mourning Cloak (Nymphalis antiopa) is the first of the butterflies at Harmony Hill to take to the air, long before March 20th arrives.
Unmistakable in appearance, the darkness of the wings surrounded by brilliant whitish yellow of the Mourning Cloak is exactly where the common name comes from. The wings resemble a person in deep mourning, cloaked by a dark garment to show sadness and loss. In parts of Europe, where this species is also commonly found, the practice of layering in dark clothing to express grief can still be seen in modern culture. The wearing of a dark dress, suit, or even veil to a funeral or wake is an extension of that. And that is what was seen in the colors and pattern of the Mourning Cloak Butterfly.
Besides being documented at Harmony Hill this species is found across North America, Central America, parts of South America, as well as parts of Asia and, as previously mentioned, through much of Europe. Just as at Harmony Hill, Mourning Cloaks are often the first butterflies seen each year. In its northerly habitats, it is extremely common to see this species fluttering about while snow is still very much on the ground. Let’s look at how this species is first out of the gate.
The answer is quite simple. This butterfly hibernates. And it is quick to awaken when temperatures begin to rise. It can very often be seen on the first warm days of the year, then retreat to a safe place to wait out any cold spells that may interrupt the march towards consistently warm days.
A member of the Brush-footed Butterfly (Nymphalidae) Family, Mourning Cloaks use two important tools to survive the coldest months. They overwinter by finding shelter beneath exfoliating bark on trees, in clusters of dead leaves clinging to twigs, and even in old, abandoned woodpecker cavities. Furthermore, members of this family are cryptically colored and use that camouflage to elude the view of potential predators. When at rest with wings folded, Mourning Cloaks can easily be mistaken for a burned piece of bark or wood.
Overwintering is not a strategy taken by most of the adult butterflies at Harmony Hill. To the contrary, most species of butterfly don’t make it to winter here, much less through the winter. If the adults of most species aren’t gone by the first hard frost, that is the final event of their short lives. That is far from the case for Mourning Cloaks; however, as this species can find shelter and survive long periods of subzero temperatures. That extreme ability to survive frigid weather is quite useful in northern latitudes, but is not something they must endure at Harmony Hill.
Another behavior seen in many of the Brush-footed Butterflies that Mourning Cloaks are known for is that they overwhelmingly prefer to lap up moisture and nutrients from puddles, decaying meat, scat, and sap from trees, instead of visiting flowers for nectar. It is not unusual to see Mourning Cloaks hanging around the holes drilled by Yellow-bellied Sapsuckers, taking advantage of the sweet liquid made available by the woodpeckers. If you think about it, that makes perfect sense, doesn’t it? Sap starts flowing in the trunks of trees when the temperatures warm up and that gets the sapsucker holes oozing, providing our early spring Mourning Cloaks with a food source!
While having the ability to survive the winter gives this species a leg up when it comes to being able to find food before most wildflowers are in bloom, it doesn’t necessarily come without its dangers. Their camouflage is effective, but not fool proof. Predation does happen. Sheltering out of the wind and where the cold doesn’t bite so hard is handy, but if the winter is particularly brutal or long, then the adults that hibernate may not make it. And the adults enter into hibernation in the condition they were in at the end of the warmth of last year. If they had damaged wings or other injuries, that physical impairment will still be there when they emerge. That might make them ready prey for predators. And the list of predators of this butterfly is long! From reptiles, amphibians, birds, and mammals to fellow insects, such as parasitic wasps and flies, Mourning Cloaks face a gauntlet of critters looking to take advantage of them as food or hosts for their own larvae!
Speaking of larvae, we know adult Mourning Cloaks feed on the fluids of trees, decaying meat, scat, and moisture on the ground; but, what of the caterpillars? At Harmony Hill, Mourning Cloak caterpillars use Black Willow (Salix nigra) and American Elm (Ulmus americana) as host plants more than anything else; but, Hackberry (Celtis occidentalis) is another host plant they will utilize.
This spring, we will enjoy seeing Mourning Cloaks as they fly around the creek and forests, knowing they will be mating and laying eggs soon. And we will be thankful for those adults that overwintered, knowing their 10–12-month lifespan will soon be over. We will delight in their beauty and grace, whether in flight or perched as they get much needed nutrients from anything but flowers. More than anything, we will be thankful as they herald the arrival of spring. Some have American Robins as their icons of spring. Of the many plants and animals we know foretell longer and warmer days, Mourning Cloaks are one of our favorites at Harmony Hill! No calendar needed when we see them out and about!
A Quiet Visit With a Golden Net-winged Beetle
Would you rather hear this article? Click on the above audio to take a short “Walk In the Woods” at Harmony Hill!
As we share our observations and discoveries at Harmony Hill, there are many things we hope you take away from each of our visits. We want you to know that some of the most interesting and beautiful things on this planet can be found a short walk from your front doors, and we would like for you to know that even plants and animals you may encounter everyday have amazing stories to tell. We would love for something you read here to encourage you to see that conserving natural resources is more important today than ever before and that making sure these things we talk about in our regular visits are here for future generations starts with each one of us.
But, more than anything, we want you to get outside and spend some time in Mother Nature. Sure, there are times we want to cover as much ground during a hike as we can, seeing as much of the splendor around us as possible. However, this week is a lesson in stopping and spending quiet moments in the woods, allowing your stillness to reveal species that might ordinarily be hidden underneath the surface.
While sitting on a fallen log and jotting down some field notes in our notebook, we listened to the morning songs of the birds and looked at some very early wildflowers beginning to break open well before the calendar would even have Spring listed on its dates. A Fox Squirrel shimmied down a Loblolly Pine and sat upon a low stump, surveying the area, and keeping a watchful eye to the sky. A Hermit Thrush hopped from the cover of an Eastern Red Cedar, quietly calling and scratching at the leaf litter. The calls of a murder of American Crows preceded the call of a Bald Eagle, as sure sign the crows were harassing the largest bird of prey at Harmony Hill. Dappled sunlight danced across the developing leaf buds of Sassafras saplings, almost like ripples of water from the heavens above.
As we finished writing the species we were seeing and hearing, preparing to return walk to another place in the forest, we saw a small beetle crawling out from underneath the carcass of a long dead Loblolly Pine. There, we saw a species that is quite common; but is often not seen due to its habits and behaviors. Conspicuous in appearance, believe it or not, this beetle is often overlooked or not even noticed by many in the woods.
This brilliantly colored beetle goes by a couple different common names; but, has just one very appropriate scientific name. Depending upon where you are in the world, you may hear this beetled called either Golden Net-winged Beetle or Red Net-winged Beetle. No matter what, we naturalists know this beetle as Dictyoptera aurora. (Before you ask, we are all naturalists here! Welcome to the family!)
First of all, let’s dive into the naming of this species. The common names might have you scratching your head a bit. What is a net-winged beetle? Take a look at the photos this week and you’ll see some very pronounced lines running down the length of the outer wings, or elytra, of the insect. Those lines have small ridges and resembled netting to early observers, giving us “net-winged” in the name. All net-winged beetles belong to the Lycidae family.
As a matter of fact, that leads us to the genus name of Dictyoptera. Quite simply, that translates to “net wing”, from the Greek “diktuon” for net and the Latin “pteron” for wing.
The “red” is obvious to most people, but what of the “golden”? In Roman mythology, Aurora was the goddess of the dawn. Any of us who have delighted at the rapidly changing skies during a beautiful sunrise can attest to the gorgeous shades of reds giving way to the golden hues of the sun as it lifts above the horizon. And, the species name is a nod to the goddess, Aurora, and her lovely golds and reds. (Side note… Au is the symbol for the element gold and oftentimes when you see Au or Aura in scientific names, it may be a nod to the color or the hue of deep yellow.)
That bright color makes this beetle really standout in the forest, especially when we look at the photos this week! It really pops against the dull late winter colors. That bright aposematic coloration serves as a warning to potential predators not to eat this beetle. Those same lines that run the length of the elytra are filed with a foul smelling and tasting chemical lacing the blood of the beetle. If the elytra are bent too much, or even broken, then this chemical that is specific to this family of beetles is released. So specific is this chemical, Lycidic Acid, that it is named after the family Lycidae. Like other beetles that expel distasteful and poisonous liquids, the Golden Net-winged Beetle can also secrete Lycidic acid from several jointed regions of its body. Lycidic acid is very effective in deterring potential predators from further injuring or eating the beetles.
So effective is this chemical deterrent that other insects, such as species of moths, have evolved to mimic the visual cues of net-winged beetles. This mimicry serves to trick predators and provides a level of protection my having similar colors, patterns and even shapes as species such as the Golden Net-winged Beetle.
In a future installment, we’ll discuss the various types of mimicry in nature, along with some examples we have at Harmony Hill. If we went off on that tangent now, this visit would be exceptionally long!
No visit with a species like this would be complete without covering diet. The Golden net-winged Beetle is right at home at Harmony Hill and the forest habitats found here. The larvae eat a variety of foods, including decaying plant material, fungi, molds, and even other smaller insects. Adults have a varied diet, as well. Though they still take advantage of other smaller insects, adult diets are mostly made up of pollen from flowers and trees, as well as nectar from flowering plants.
This adult Golden Net-winged Beetle was crawling out of a downed and decaying pine snag, which could mean it was either laying eggs or even looking for a mate. Sexes look similar, but the species is pretty easy to identify. They are between ¼” to just under ½” in length, they have the obvious lines down their elytra, are a lovely shade of crimson to lighter red, and they have the identifiable black spot on their thorax that extends to just onto the abdomen. Their antennae and legs are uniformly black and obviously segmented, clearly contrasting with the bright body.
Some days are busier than others and some mornings we feel compelled to walk farther and faster. But, we must remind ourselves that much of the beauty around us takes time to appreciate and observe. It is good to dwell a little longer and see what Mother Nature has to reveal. Had we gotten up even a moment earlier the other morning, we would have missed seeing this lovely woodland resident. So, please go outside and stay in that wonder for a few minutes more than you planned. Sit in those moments and notice something you may have previously overlooked. It might be a beautiful red beetle, or it might be another story Mother Nature wishes to tell. Just be sure to look and listen. If you do that, then the lessons of our visits are truly taking hold. And, for that, we thank you.
A December Surprise and Mystery Moth
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It has been a rather warm winter at Harmony Hill and, even with some chilly nights, the days have been sunny and very pleasant. Shortly after sunrise, the radiant heat of the sun brings the temperatures up and we often bask in that lovely yellow glow. Just as we have enjoyed the warm days extending towards the end of the year, it is clear we aren’t the only ones in the forests taking advantage of the delightful rays. Turtles sit on logs in the creek, birds flit around during the shortened days and we’ve even seen dragonflies darting around as they hunt. Reptiles and birds aren’t unexpected as we prepare to turn the calendar, but the levels of insect activity we’ve seen is a bit of a surprise.
It is true that we never truly get cold at Harmony Hill, especially when compared to the northeast, upper Midwest, and Rocky Mountains. We rarely see snow and single digit temperatures are unheard of here. However, we’ve typically seen a few hard frosts by now and insect activity is usually diminished. This December has been different and one morning, we were quite surprised to find an insect well outside of the timeframe it would be expected.
Not only are we going to talk about an observation that was unexpected, but we’re also going to look at a genus of insects we know very little about. You see, there’s still magic out there in nature and we aren’t even close to knowing all the answers to many of the mysteries she holds close to her vest.
There are places in the forests of Harmony Hill where Eastern Red Cedars (Juniperus virginiana) grow in small stands. The beautiful, deep green backdrop provided by these evergreen trees is a welcome scene this time of year. Most of our oaks, hickories, ashes, and dogwoods have dropped their leaves for the season; and the majority of the pines here are tall enough that they hold their needles well above our heads. But the cedars bring their emerald curtain limbs and needles low to the ground. It was against that verdant screen that a bright yellow spot caught our eye.
Walking towards that contrast in hue, we began to smile as we realized it was not a dead leaf, but a moth that grabbed our attention. And this moth was a couple of months beyond when we would normally see it on the wing.
Geometer Moths (Family Geometridae) are not as vivid as some species of moths, such as Regal Moth (Citheronia regalis) or Luna Moth (Actias luna); nor do they fly with the flair of their Sphinx Moth (Sphingidae) relatives. But they have a subdued beauty all their own and, believe it or not, they are one of the first moths you learn about as a child.
You see, the word “geometer” translates to “earth measurer” and that is one incredibly fitting name for their caterpillars. The diminutive inch worms we encounter as children, of which there are thousands of species, eventually metamorphize into geometer moths!
There are many superstitions associated with the caterpillars for geometer moths. It was believed they measured the ground as they inched along, giving them their name of “earth measurer”. One particularly morbid old wives’ tales even said that, should you see an inch worm crawling on you, it is measuring you for your coffin!
Have no fear. There is no evidence, whatsoever, that this is at all true!
One thing all geometer moths have in common, regardless of species or location, is a fairly cryptic coloration and pattern meant to blend into their surroundings. That slight camouflage can be seen in the photo of our moth. The brownish spots are irregular and break up the line of sight of a potential predator. In fact, when perched against dead leaves, the moth can be nearly invisible. That is something we see regularly in the Lepidoptera Order of insects, which includes butterflies and moths. (Lepidoptera translates to scale-wing. Ever handle a butterfly or moth and notice a dusty residue on your fingers? That is the scales from their wings and, if enough of those scales are lost or damaged, they can lose the ability to fly.)
Now, in all of this, you’ll notice we have yet to tell you which species this moth is. That’s because we aren’t entirely sure! The best we can do is offer you the two most likely species it might be! Part of being a good naturalist is to admit when you don’t know something and to embrace the unknowns in nature. You see, we don’t have to go to tropical rainforests, distant islands, or faraway locations to find mysteries in nature. Today, we embrace one of these mysteries.
This moth is either the False Crocus Geometer (Xanthotype urticaria) or the true Crocus Geometer Moth (Xanthotype sospeta). We can’t be sure! They look identical, fly exactly the same way, and are found in the same habitats! They’re even genetically the same!
Without dissecting this moth and looking at very specific and intricate differences in genitalia, there’s very little we can do to differentiate the two. Perhaps, if we were lucky enough to find the caterpillar feeding on one of the few host plants that doesn’t overlap between the two species, we could more readily identify exactly which we observed. The fact of the matter is, we don’t have the equipment to effectively dissect and study the genitalia and we didn’t see the caterpillar on a plant that might clue us in. Therefore, we share the excitement of not being certain! And we encourage you to get excited about what is yet to be discovered as absolute!
It is likely that the caterpillar of this moth may have fed on the leaves of goldenrod (Solidago sp.) or dogwood (Cornus sp.) at Harmony Hill. But, we have yet to document the caterpillar of either specie feeding here, yet.
Finally, we mentioned earlier that we were shocked to see this moth flying around in December. The latest we have observed this genus of moth on the wing was mid-October, and that was considered later than normal. The usual flight for these moths is from April to September; so, seeing it in December was both an unexpected delight and quite a surprise. It could be that these later observations will become the new normal, as climate change pushes warmer temperatures later into the winter and much earlier in the spring at Harmony Hill.
This is where our walks in forests and fields become more important, not just for our mental health; but, for understanding the current state of natural history for our area. What a wonderful thing! To clear our minds and expand our understanding of nature, all in the act of being out in our wonderful Harmony Hill.
A World Within Worlds: How Berries Grow Caterpillars and Wasps
During our visits with each other, we have spoken about how the past feeds the present and the present foreshadows the future. Mother Nature is both a caring nurturer and a stark reminder of the struggles of life. She is also a fortune teller and can give you hints as to what was once here before us, as well as what is just over the horizon of time. Just as we spoke about a new generation of the forest beginning when a nurse tree died and a woodpecker began drilling holes in the decaying wood, we will once again look at a serendipitous moment of nature rippling out across time and opening opportunities for species not yet on the landscape.
A couple of generations ago, right around this time of year, a bird ate the delicious and eye-catching purple berries of a native shrub. What bird ate that berry, we will never know. It might have been an American Robin. It may very well have been a Wood Thrush. For all we know, it could have been an Eastern Towhee, a Northern Mockingbird or even a Northern Cardinal. The exact species isn’t important. What is important was that one of our winged wonders consumed the lavender-colored fruit of the American Beautyberry (Callicarpa americana) and then chose to fly to Harmony Hill. And when they were flitting around the forests of this gorgeous ground, they defecated the seeds hidden inside the berries. Upon falling to the soil below, one or more of these seeds germinated and began what would become a healthy population of American Beautyberry on Harmony Hill. That moment brings us to today’s lesson on insects, caterpillars eating leaves, moths pollinating flowers at night and how wasps use the scent of injured leaves to find a host for their eggs and larvae.
There are several places on Harmony Hill where American Beautyberry can be found growing in dense hedgerows, providing shelter, habitat and food to a variety of species. These ecotones not only sit between the forests and open areas at Harmony Hill, but they also represent their own worlds within worlds. By simply looking a little more closely, we can see the same give-and-take of nature that one would normally expecting on a grand scale; just in the micro ecosystem created by this native plant.
When summer begins to yield to fall, the clock of nature seems to tick a little more rapidly and loudly. Many species of plants seem to be in a hurry to get their seeds ready to cast out into the world and many species of animals appear to have a bit more urgency to preparing for the colder and shorter days ahead. It is in that backdrop that we found today’s Nature Note playing out. The stem of an American Beautyberry looked awkwardly bare, sticking out from stems covered in leaves. When we stopped to see what might have caused the stem to be stripped of its greenery, we observed a caterpillar we thought might very well be grazing away. The Rustic Sphinx Moth (Manduca rustica) caterpillar was eating nonstop as we peered into the shrubbery.
A member of Sphingidae family of moths, Rustic Sphinx Moth caterpillars are often lumped into the group of caterpillars called “hornworms” by many. Indeed, the “tail” of the caterpillar resembles a horn emerging from the rear of animal. That protuberance is an easily identifiable field marking shared by other familiar caterpillars, such as the Tomato Hornworm (Manduca quinquemaculata) and the Tobacco Hornworm (Manduca sexta). However, the tail of the Rustic Sphinx Moth caterpillar shows us how we can differentiate this species from his common cousins. Indeed, the caterpillars all look quite similar. While the “tails” of the Tomato Hornworm and the Tobacco Hornworm are smooth, the tail of the Rustic Sphinx Moth caterpillar is rough-looking (or granulated). Furthermore, American Beautyberry is a major larval food source of this caterpillar, making identification easy!
When it completes all its development, through several instars, the caterpillar will either climb down to the soil level or simply fall to the ground. Once there, it will burrow its 7”-9” body into the soil. When it settles into its subterranean setting, it will form a pupation chamber loosely around itself. There, it will go through metamorphosis and become an adult moth. The process will start over, as the adult female moths will lay their eggs on host plants for the caterpillars to start eating once they hatch.
Like so many of the Sphingidae moths, the Rustic Sphinx caterpillar will become a cryptically colored moth that takes to the skies in the evenings and feeds on nectar throughout the night. A mixture of grays, blacks, whites and browns cause this moth to blend into the barks of trees and the ground while at rest. However, when it takes to the wing, it looks eerily like a hummingbird. This leads to the common name of “hummingbird moth” this species shares with other members of Sphingidae. The only pop of color found on the adult is a series of orange dots on either side of the abdomen of the moth. Other than that, it relies and uses its camouflage to hide for potential predators.
There are a variety of plants that use Sphingidae moths to pollinate them, all of which have evolved long channels in their flowers that keep nectar away from all but the longest proboscises found on Hawkmoths. Members of the lily and evening primrose families are pollinated by Rustic Sphinx Moths, as well as the moths of other hornworms. These plants that attract Hawkmoths are called “sphingophilous” plants.
When we found the caterpillar in this installment, a rather obvious species was at work and became part of the story. As you can clearly see in the photos, there is something odd happening. What are those white, fuzzy things all over this hornworm? Remember when we told you there is a world within a world right inside the American Beautyberry? Well, here we see it! Let’s look a little closer and see what is going on!
There is a tiny parasatoid wasp patrolling the forests and fields of Harmony Hill. And this wasp is always sampling the air for scent molecules to find a host for its eggs and larvae. But, it isn’t keying in on the smells associated specifically with a host. Not at all. Instead, Cotesia congregata is on the hunt for chemical signals from injured leaves of American Beautyberry plants. Why would it do that? Well, where there are large areas with chemical cues of injured American Beautyberry leaves, there is a good chance this wasp will find the soft and large body of a hornworm just munching away at the leaves. And it is that caterpillar body in which it will lay its eggs!
Wait! It gets better!
When the female wasp finds a suitable host, like the hornworm in the photos, it begins inserting its ovipositor into the caterpillar to lay between 50-75 eggs. Along with the eggs, the female wasp injects a type of bracovirus inside, along with its venom. This polydnavirus works in conjunction with the venom to halt responses from the caterpillar’s immune system, effectively preventing the host’s body from attacking or working to ward off the wasp’s eggs. It also prevents any type of clotting of the hemplymp, or what many would consider the “blood-like” fluid in the caterpillar. That allows the developing larvae to consume the hemolymph. All these factors also inhibit any further development of the host, causing it to eat and live on; but, not allowing it to develop into an adult.
The wasp larvae develop just under the skin of the hornworm, feeding on the hemolymph unit it is time to emerge and pupate. This usually takes about 7-10 days.
They will burrow out of the hornworm and plant their tiny, white cocoons atop the caterpillar. They stay in their cocoons for about a week, before emerging as adult wasps.
And to think, this amazing story all began decades ago when an unsuspecting bird ate a berry and then flew to Harmony Hill! When we look at where the wasp pupa came from, we must look at the Rustic Sphinx Moth laying its eggs on an American Beautyberry. When we look at where the moth and caterpillar came from, we must look at the hedgerows of beautyberries on the land. And, when we look at where they came from, we are back to our unknown bird perching on a branch and defecating seeds onto the soils of Harmony Hill! Mother Nature is fortune teller and can show you the past, present and future… if you’re willing to stop, look, listen and heed her clues.
Summertime Scratching
If you are a regular reader, you have probably noticed we try to invigorate our readers with the wonder of nature and we try to excite curiosity in everyone in every story we tell. Much of this is done through peeling back layers of the science of some of the species we have at Harmony Hill, hopefully giving you a few glimpses at nature that make you exclaim, “I didn’t know that!” This installment is designed to spotlight a genus of arachnids that we are certain you know, but one that is often shrouded in myth and old wives’ tales. And, when we’re done with our conversation, we hope you’ll be able to say, “Hey… I didn’t know that!”
Summertime brings warm weather, sunshine and a longing to be outside more than usual. We are all walking through the fields and the forests more, cookouts and picnics find us eating in the great dining hall of nature and, even drives are more outdoor focused, as windows are down, sunroofs are open and convertible tops are dropped. And, like you, those extra hours walking in the woods and those picnics may invariably find us scratching some itchy, red bites on our ankles, waist and the backs of our knees.
Growing up, our parents and grandparents often warned us about sitting in pine straw or walking in tall grass. Whether they called them “chiggers” or “red bugs”, they would tell us horror stories of bugs that will bite you, bore into your skin and cause you intense itching for weeks! For those of us not wise enough to heed their advice, we did find ourselves itching, scratching and suffering from bites we were told could only be healed by thorough and thick applications of fingernail polish.
Some of the advice they gave us was true; but, much of what we were told of “chiggers” or “red bugs” was not based on fact. Let’s look more closely at the natural history and see what the fact are and dispel a myth or two along the way.
First of all, what is a chigger? Chiggers, or red bugs, are not insects at all; but, are arachnids that are more closely related to scorpions and ticks than they are to mosquitoes. Classified as a type of mite, adult chiggers, found in the Eutrombicula genus, exhibit the classic arachnid characteristic of eights. Adult chiggers, of which there are dozens of species, are also red in color, giving them their common name of “Red Bug”. However, many species of adult mites can be reddish in color and that is not a definitive identifying field marking.
Rather small arachnids, adult chiggers measure about 1.25mm (0.05 inch, or 1/20th of an inch) and become active when ground temperatures reach about 60F (15.5C). For much of the southern United States, that is a large chunk of the calendar year, making chigger season March-November, most years. Adults can be seen by the naked eye and, perhaps, you’ve seen them crawling along blades of grass. Adult chiggers pose no threat to us, as they do not bite or feed on humans. They do; however, make a very. Good living feeding on other insects and even insect eggs.
If adult chiggers aren’t the problem, then what is?!
For that answer, let’s look at the life cycle of this arachnid.
There are four main stages in the life cycle of a chigger: egg, larva, nymph and adult, that usually occur over the course of a couple of months. However, depending upon the time of year and the location, it may take nearly a year to complete the life cycle. (There is also a very short, but recognized prelarva stage in some mite species.) We can take the egg stage of the life cycle out of the conversation, as the eggs are of no danger to humans. The nymph stage is very similar to the adult stage, also having eight legs and the same diet as the adult. That leaves us with the unique larval stage, with just six legs and a hunger for semi-digested skin cells, as our culprit!
The larval stage of the chigger, as mentioned, is quite different from the adult. Having just six legs, it is also considerably smaller. Chigger larvae measure an incredibly tiny 0.25mm (that’s just a miniscule 0.001 inch, or 1/100th of an inch!) I had a professor in college once say that you could easily fit 4-6 chigger larvae inside a 12-font period! (Just like the one under the exclamation point you just read)
Adult female chiggers will lay eggs on vegetation and, when they hatch, the larvae are not very mobile. This means they will be found in large numbers in very specific areas. This clumping is why chigger bites come in such large numbers and why you sometimes get no bites in the same geographic area. It is not an exaggeration to say you could have well over 100 chigger larvae in one spot and have absolutely none just a few feet away.
Chigger larvae thrive in moist, shady areas, where grasses, forbs and other vegetation is found. They are particularly fond of creek and stream banks, where tall hardwoods keep shade over vegetation below. Some chiggers can also be found in areas that seem much drier, such as in mulch (think pine straw).
The larvae will sit on that vegetation and wait, indiscriminately, for any potential victim to walk past to feed upon. And, it is that feeding that leads us to the bites that itch so badly and are prone to become inflamed and even infected. The larvae will climb up onto the animal (or human) and find a thin portion of skin to bite.
They do not have strong mouthparts and must find a thin place to pierce the skin. In most mammals, that is usually at a hair follicle. On humans, that is around the ankles, the beltline and groin area, the backs of knees and armpits. That also coincides with where clothing fits the tightest; where socks, belts and sleeves sit. When they bite, they DO NOT burrow into your skin and stay there to feed and irritate you. They do; however, excrete saliva that dissolves skin cells, and it is that liquified cell structure that they feed upon.
Your body’s natural immune reaction even helps them with this process. The red dot atop the bite is the top of a structure called a stylosome, which is a hardened tube that allows the digested skin cells to flow out of your body. The stylosome becomes a straw in which the chigger larva can sit and feed.
Unlike their tick relatives, chigger larvae do not have mouths that are designed to allow them to latch and hold on with strength. They can be brushed away and one of the easiest ways to get them off you is a good soapy shower or bath.
The larvae can sit on victims for as many as 2-4 days; but, that is very rare with humans. Most humans only have chiggers feeding on them for a couple of hours. By the time the itching begins, the damage has been done and the body’s histamine response is in full force. Itching and swelling begin a few hours after the bites and can become intense and continue for several days. It is important to wash very well after being in chigger habitat and it is important to take steps to prevent bites to begin with.
By wearing long clothing, tucking pants into socks and shoes, avoiding taller vegetation and not sitting or lying in places where chiggers can be found, you can minimize the opportunities for them to crawl on you and bite you. If you use a repellent of any kind, it is best to pretreat areas around the shoes, ankles and beltline before going out.
As far as treating bites that have happened, simple topical treatments for itching work best. Fingernail polish does not smother the chigger, as they do not burrow into your skin at all. However, be mindful not to scratch the bites aggressively and risk infection. Secondary infection is the most common medical issue after chigger bites become present.
An artist’s rendition of the adult stage of the chigger (left) and the larval stage (right). Image courtesy of Texas A&M. https://extensionentomology.tamu.edu/publications/chiggers/