Late Summer Spiders
August brings more than just heat and humidity to Harmony Hill. Along with many evenings spent watching lightning dance across the sky and, with any luck, the sound of rain falling on the landscape, we notice increased insect activity in the fields and forests. This increase in insect activity serves to fuel more than a few other species that feed on insects large and small. Whether it is the diminutive Blue-gray Gnatcatcher or slightly larger Acadian Flycatcher, we see birds working continually to dine on insects. Birds are not the only animals feeding while the bounty grows in the summer sun. Reptiles and amphibians eat their fill on fenceposts and along the edges of creeks. Other insects, like dragonflies and damselflies take part, as well. But, one of the most recognizable groups of animals are seen more and more this time of year, capturing insects and working to prepare for the next generation. As we walk in the woods and notice the days shortening ever so much each day, it is not uncommon to get a face full of spider web. The orb weavers are out, and we love seeing their artistry and bask in the utility of their beautiful work. There are many spiders at Harmony Hill, but this week, let’s look at two of the more eye-catching species we have.
Of the most skillful web builders found in the lower piedmont, these two species of spiders are certainly two of the most accomplished. The Giant Lichen Orb Weaver (Araneus bicentenarius) and the Marbled Orb Weaver (Araneus marmoreus) grab your attention immediately with their beauty and are each capable of constructing webs several feet in diameter. Both species have been observed at Harmony Hill and we expect to see them through early autumn.
Giant Lichen Orb Weavers are aptly named, as they are colored exactly like balls of lichen with eight legs. That is not by accident. They are found in wooded areas, much like the mixed pine-oak-hickory woods found throughout much of Harmony Hill. Many of these trees have green and gray lichens on their trunks and limbs, which look eerily like the colors and patterns found on (Araneus bicentenarius). Or should I say, the Giant Lichen Orb Weaver looks eerily like the lichens found on the trees in the woods it inhabits.
First described in 1888 by Rev. Henry McCook, a naturalist and Presbyterian pastor from Philadelphia, the Giant Lichen Orb Weaver is found from central Canada, south to Texas and over to the east coast of the United States. 1888 saw Philadelphia celebrating its own bicentennial and Rev. McCook was such an ardent Philadelphian that the species name of "bicentenarius" is a nod to the bicentennial of his favorite city.
The Marbled Orb Weaver is often referred to as the "Halloween Spider" or "Pumpkin Spider" by some. Being colored orange and black, it doesn't take a lot of imagination to see the resemblance this species bears to a Jack-o-lantern. The dark markings on the orange abdomen of the spider give us both the common name of "marbled" and the species name of "marmoreus", which is Latin for marble. The timing of seeing them in the forests of Harmony Hill also lends to the Halloween Spider nickname, as we begin seeing it in late summer and their numbers increase through very late summer. In early fall, and even all the way to the end of October, female Marbled Orb Weavers can be found in the forests; coinciding with that fabled fall holiday on October 31st.
Both species belong to the genus Araneus, which is taken from the Latin word for spider. While there are many types of orb weaving spiders (seriously... orb weavers compose a little better than 1/4 of all spider species), Araneus spiders are separated from other orb weavers by their rounded and/or angular "shoulders". But, the shoulders we're talking about are not in relation to any of their eight legs. Nope. These shoulders are protuberances, or bumps, on the abdomens of Araneus spiders. Take a look at the photos of the spiders from above and you can see the bumps on either side of the abdomen of the spiders. They appear to be more like dimples on the Marbled Orb Weaver, but are “shoulders, nonetheless.
Araneus spiders are not known for hanging out in the middle of their orbs during the day. Unlike their orb-weaving cousins, the Argiope spiders, who post up for all the world to see, Araneus spiders retreat to the seclusion and protection of a hideaway near their webs. These hiding spots may be clumps of dead leaves, exfoliating bark or anything else that will conceal it from potential predators.
When an insect enters the web, the Araneus spider will quickly leave its hideout and run down a dry escape line to subdue its prey. We all know how sticky spider webs can be, but have you wondered how they get that adhesion power? Well, it’s as simple as the silk being manufactured in four silk glands and then spun through six spinnerets. Then, the capture lines, those circular lines which comprise the hubs that go around and around the web, are coated with a glycoprotein as they are spun. That extremely sticky glycoprotein is also covered in an aqueous layer as it adheres to the capture lines being spun, allowing this capture lines to retain their adhesive properties as the web sits out in the drying conditions of the wind and sun.
The long, straight lines which radiate out from the center of the web and anchor the web to the structures it is built from are known as radial lines. They serve as the frame on which the orb can be built.
Much more common and noticeable in the fall of the year, these two spider species are harmless to humans and do a terrific job of consuming large numbers of insects during their lives. Both species lay eggs in the autumn of the year, with the young hatching in the spring of the following year.
Next time you’re out walking in the woods and you happen to get a web firmly planted to your face and head, instead of getting upset at the spider, remember you are in its home and it is serving a wonderful pest control function. And, if that spider happens to be a Giant Lichen Orb Weaver or a Marbled Orb Weaver, take a few minutes to soak up the beauty of the spider and the lovely web it has woven.
More on our orbweaver and spider friends at Harmony Hill in the coming weeks! There are so many more spider stories to tell!
Wildlife Signs Woven on the Winter Landscape
Would you rather hear this article? Click on the above audio to take a short “Walk In the Woods” at Harmony Hill!
When it comes to seasons, winter often gets a bad rap. Summer seems to get all the attention, with its longer, lazy, and warmer days. Autumn is a time to watch the beautiful colors of the leaves as they change, as well as enjoy the bounty of the harvest. Spring is a time of colorful wildflowers and much of its allure can be seen as a rebuke of winter. The images of rebirth and new growth are directly attributed to surviving the starkness and coldness of winter.
But we find peace in the quiet and solitude of the naked forests of winter. The crisp mornings, adorned with frost on the landscape, excite the senses in ways that the other seasons just cannot. The shortened days bring a sense of gratitude for what can be accomplished in the abbreviated daylight of winter. And, as we have spoken of in previous posts, there is an ability to see and hear more without the distractions of butterflies flitting, leaves blowing in the breeze, insects calling, and watching our step in places we know copperheads, cottonmouths and rattlesnakes are apt to be napping the day away.
While it is true that animal activity is much less during the colder months of the year, signs of the inhabitants of the woodlands of Harmony Hill abound if you slow down and pay attention. Sure, there are tracks that show the well-traveled trails of White-tailed Deer, Coyote, Wild Turkey, and even Beaver. A look at the snags we encounter will most certainly show us that Downy Woodpeckers, Red-bellied Woodpeckers, Northern Flickers, Red-headed Woodpeckers, and Pileated Woodpeckers are still foraging and excavating cavities. There are other signs that we see on our walks, some that others may walk past and not notice. Today, let’s look at clear signs we saw while checking out an area of the forest.
The morning sun was bright and clear as it tickled the edge of an opening, the shadows of the pine needles danced on the broom sedge and blackberry briers. The color brown was well represented, as all shades from chocolate to sandstone were seen in a short stride. In those gradients of khaki and pecan, a nearly perfectly round shape caught our eye. Exquisitely camouflaged in the vegetation was a sign of a different kind. Well-hidden from our view, as well as the attention of potential predators, was evidence of a species whose adults are absent from the cold winter days at Harmony Hill. But the next generation sits, waiting for the right conditions to come along. This round form, roughly the size of a ping pong ball, is the egg case of the Black-and-Gold Garden Spider (Argiope aurantia). And just as a footprint in the soils along the creek show us deer have recently been there, this egg case was a sure sign of this species of beautiful spider.
Most of us have encountered these spiders during our time outside. They are a common species and, even if you don’t see the spider in the summer or fall, their webs are a thing of natural wonder and splendor. Belonging to a group of spiders known as Orb Weavers, they weave impressively large wheel-like webs. (More on orb webs and orb weavers in a future installment!)
Sitting in the middle of their large, round webs in broad daylight, these big spiders sit with their legs paired up. Two legs sit high and to the left, two legs sit high and to the right. Two legs sit low and off to the left, two legs sit low and off to the right. And the center of the web sports a zigzag pattern that looks as though the spider doodled a zipper where it perches. Some people even call spiders in this genus “Writing Spiders” or “Etching Spiders”, because it looks like they practice writing or etching in their webs. There is even an old superstition that, should you ever see your name written in the spider’s web, your number would soon be up!
But they aren’t really writing or doodling in their webs. What is all that zigzagging about, then? That bit of structural architecture in the web is called “stabilimentum” and there are several thoughts as to what it does.
It may serve as a visual cue for large animals, like birds and mammals, to see the web and avoid it. By deterring birds from flying through their webs or keeping deer from walking in the middle, the spiders are able to keep that insect catching web intact and not have to rebuild immediately after completion.
It may serve as a visual cue to attract insects, drawing the very prey they seek to catch even closer to the sticky threads.
It may serve as a way to increase structural integrity and strength, while also increasing vibrations the spiders feel when an insect becomes trapped.
As you know, when it comes to nature, there is seldom just one reason. When something serves multiple positive purposes, nature rewards it and that attribute is then passed along. It is likely stabilimentum does all this and perhaps more!
Either way, when one of the Argiope spider webs is encountered, it is difficult to mistake. But that web is long gone from Harmony Hill by this time in the winter. How do we know who left this egg sac?
Female Black-and-Gold Garden Spiders, also called Black-and-Yellow Garden Spiders, spin these spheres of silk as a place to hold their eggs and protect them after they die. Other Argiope spider egg cases may be large and impressive, but at Harmony Hill, only the Black-and-Gold Garden Spider egg sac is this shape and size.
Want to see another species we have here as a comparison? Well, thanks to Mother Nature, we can do just that!
Stuck in the middle of some twigs and vegetative debris, we saw a weirdly shaped object hanging there. Looking every bit like the nucleus of a cell that exploded or an amoeba on steroids, the egg case of the Black-and-Silver Garden Spider (Argiope argentata) is completely different from its golden cousin.
Just as common here, the Black-and-Silver Garden Spider can be found in similar habitat as the Black-and-Gold Garden Spider. They even spin extremely similar webs, stabilimentum and all! But when it comes time to lay eggs and spin a protective case, instinct kicks in and they spin an amorphous take on a polygon instead of a perfect golf ball.
Adult spiders of both species look similar, but the silver and gold accents on each area provide a definitive way to identify them in the field. Their species names even help with the identifications, as aurantia means covered (or inlayed) with gold and argentata means silvery!
The genus name of Argiope is a little more complicated, with its roots in Greek mythology. Argiope was a nymph and the mother of poet and singer, Thamyris. Her name translates to “Silvery Face” or “With Bright Silver Face” and that silver face can be seen on spiders of this genus, if you use a lot of imagination.
So, our Black-and-Gold Garden Spider’s scientific name can be translated as “with a silver face and covered with gold”, while our Black-and-Silver Garden Spider’s scientific name can be translated as “with a silver face silver”.
Finally, there are many beliefs and even superstitions related to these spiders. Some old southerners believe that, should you ever find your name written in the web of one of these spiders, your number will soon be up.
Going back much farther on the land now known as Harmony Hill, there is a Native American belief in the female deity Old Woman Who Never Dies. She was often depicted in iconography as an Argiope Spider, appearing on gorgets and drawings with the diagnostic paired leg posture. Of the many things Old Woman Who Never Dies was responsible for, she wove the Milky Way across the sky, and it served as a bridge for souls to cross over from this world to the above world. In fact, when the Milky Way dips to its lowest point in the sky each year, that is when all the souls who passed the previous year could walk to the edge of this world and cross the bridge that Old Woman Who Never Dies spun to the above world. (This is, of course, a very simplified version of that belief.)
Indeed, not only were these lovely spiders not feared by people here long before us, they were part of a revered and critical transition for souls. Consider that next time you see one of these massive orb weaving spiders!
Smaller Orb Weavers: Similar, But Not The Same
With all projects and efforts, it is good to occasionally step back to revisit the purposes and end goals of what you’re doing. At Harmony Hill, we see these “Nature Notes” as a vehicle to ignite curiosity, to show the wonders of nature and to help teach identification techniques to our fellow naturalists. From time-to-time, we like to spotlight species that may not be anyone’s favorite (our discussions on snakes are a prime example); but, have a unique beauty and wonderful purpose on the landscape. A couple weeks ago, we talked about late summer spiders that are showing up at Harmony Hill. The spiders in that post are harmless to humans, yet are still feared by people. We hope the post opened a few eyes to the purpose these amazing architects serve as pest control in the forest. This week, we hope to shine a light on a couple more species that are often mistakenly identified and who both help keep insect populations in check as the late summer days give way to early fall.
As we’ve previously discussed, the most obvious spiders this time of year are the orb weavers. For clear reasons, their ornate, beautifully functional, and ingenuously built structures draw our attention to them as we walk from fields to forests. Every now and then, our attention is drawn in as we get a face full of their spun silk! Even we find ourselves flailing and pulling web from our face and head, as though we are fighting some invisible enemy who attacked us. Let’s take another look at who might be building some of those webs, how to identify them and see how they’re helping us… even if we don’t realize it as we jitterbug and swing around with spiderweb all over our face.
Sometimes, we get asked about “crab spiders in big round webs in the woods”. We know immediately it is likely one of two spiders, even though neither are actually crab spiders. However, due to their appearance, we know why some make the distinction that they might be. True Crab Spiders belong to the Thomisidae and do not build webs. They are found hiding in flowers and on plants, giving them another common name – Flower Spiders. When we hear “crab spiders in big round webs in the woods”, we can take the clue of web and exclude Thomisidae spiders. With that same clue, we can instead focus our attention on the two spiders we’ll look at in this post!
Looking very much like a crab, the Black-and-White Spiny-backed Orbweaver (Gasteracantha cancriformis) can be found hanging out in its orb-shaped web during daylight hours. The hardened exoskeleton has spiny protrusions around the abdomen, giving it a fierce look. That hardened exoskeleton is a great protection from predation, as it can withstand a great deal of pressure for an animal so small. And the spines are capable of piercing soft tissues, like gums of predators and thinner-skinned areas of a potential predator’s body. These spiny-backed spiders come in a variety of color morphs (polychromatic), from black and white, to black and yellow, and even black and white, with red!
The resemblance to crabs isn’t simply limited to appearance, as the scientific name even alludes to the similarity. The genus name of Gasteracantha refers to spiny (acantha) stomach (gaster), while the species name of cancriformis means “taking the form of a crab”. Cancri is a direct reference to the crab constellation, Cancer, while formis means “in the form of”.
When you find an orb web in your walks in nature, take a look around the edges of the web. Do you see more pronounced and thicker white dashes all around the perimeter? If you do, you may very well be dealing with this species, as members of the spiny-backed family of spider place morse code-looking dashes and dots along the exterior of their orbs. You might wonder why they do such a thing. Well, the prevailing hypotheses are that the dashed allow the web to be more readily seen by birds and, therefore, won’t be destroyed by something far too big to capture flying through, and that the dashes may steer insects more towards the center of the web. As is often the case in nature, and as we’ve talked about in the past, it is likely more than one reason and is a combination of those.
Looking somewhat similar to our first species, yet a member of an entirely different genus, we have another crab-like spider. The Arrowhead Orb Weaver (Verrucosa arenata) is another species we consider when given that “crab spider n a big round web” description. The common name is an obvious nod to the arrowhead-shaped abdomen, with the genus name of Verrucosa being a reference to it looking like a wart. The translation of the species name could be a nod to it having an overall sand color (arena means sand), or it could also bear reference to it being a spider (Araneus means spider and spiderweb).
Continuing the complication of similarities to our first species, this spider is also polychromatic! The females have abdomens that might be white, yellow, or pink! Unlike (Gasteracantha cacriformis), this spider does NOT have spines. And, more importantly, the Arrowhead Orb Weaver sits with its head facing upwards almost always as it rests in the web. The other orb weaving species of spiders in our area sit in their webs with their heads facing down and their abdomens facing upwards!
Finally, let’s talk about how important these spiders are to pest control. They are considerable smaller than the orb weavers we talked about a couple weeks ago and their webs are smaller. With those smaller webs, the radial lines are closer together and capable of capturing much smaller prey. If we told you these spiders are important for controlling mosquitoes and other biting insects, would you begin to see how critical they are at keeping pest populations in check? We kind of thought you would. And it is true! These two species do capture and eat considerable numbers of mosquitoes and small biting insects, making them great friends to have in the forest. (Even if we do walk face first into their webs!)