According to the Annotated List of Ohio Spiders published by the Ohio Biological Survey in 2021, our state is home to 682 species of spiders (order Araneae). Many reach maturity in late summer to early fall which is why they are so common at this time of the year.
On the other hand, spider populations appear to be highly variable across Ohio this season. For example, during today’s BYGL Zoom Inservice, Pam Bennett (OSU Extension, Clark County) noted that funnel weaver and sheet weever spiders are virtual no-shows this season in her neck of the woods. I note below that two of our largest-sized orb weavers, the Yellow Garden Spider and its equally showy cousin, the Whitebacked Garden Spider, are hard to find in southwest Ohio.
Spiders eat insects and other arthropods and play a significant role in suppressing forest, landscape, and agricultural pests. They also eat pests that threaten human health such as mosquitoes. A paper published in 2017 suggests that the annual worldwide prey kill of spiders ranges from 400 to 800 metric tons.
Spider Table Etiquette
All spiders share some common eating habits. Whether spiders depend on prey blundering into a web drawn from the spider’s spinnerets or the prey is actively hunted down, spiders grab their prey with their front legs and two specialized structures called pedipalps that flank their mouths. The pedipalps also function a bit like antennae helping the spider to sense their environment including assessing their food.
Next, the spiders jab their fangs (chelicerae plural; chelicera singular) through the exoskeleton of their arthropod victims to deliver neurotoxic venom to hasten the demise of their struggling quarry. Some venoms also include a kicker of digestive enzymes that initiate the dissolution of their prey’s tissue.
Spiders that capture their prey in webbing commonly add another step to their feeding etiquette. When a victim becomes entangled in their webs, the spiders rush over to rapidly spin their hapless prey as they wrap them in a thick shroud of dense webbing. They usually stop now and then to inject venom, then continue the twirl of death.
Finally, spiders regurgitate digestive enzymes from their stomach and spew the noxious brew over their victim while using their chelicera to break apart the exoskeleton. The external digestion turns their food into a goo sucked up through the spider’s tube-like mouth aided by a pumping action originating in their stomach. Some spiders are neater eaters and leave the exoskeletons almost intact.
Jumping Spiders Abound
Although spiders are known for producing silk webs, a significant percentage are "wanderers.” They hunt down their food rather than hanging around a web waiting for meat items to blunder into their sticky trap.
The hunters include Jumping Spiders (family Salticidae) with their multiple forward-focused eyes … all the better to see you with. These spiders often appear to have faces; some even look like they’re smiling.
At last count, the jumping spider family included over 6,000 described species worldwide. This represents 13% of all known species of spiders making the family the largest in the order Araneae.
Sometimes, jumping spiders just sneak up and grab their prey with their strong front legs. Other times they use their powerful hind legs to launch themselves towards their prey. Before their victim can say, "What the …?", the spider grabs its prey and dispatches it with an injection of paralytic venom. Powerful venom supports the outsized aspirations of these small ambitious spiders allowing them to take down large prey.
Even though jumping spiders don't produce a silk web, they do use silk for other purposes. For example, they use silk to form small structures, often binding together pieces of plants, to spend nights and shelter from bad weather. Their silk sanctuaries also provide a safe place to deposit eggs and protect hatchlings (spiderlings) until they can leave the nest. Females of many species will even remain inside their abodes to protect their eggs until they hatch.
Jumping spiders also use silk to avoid randomly flying off into the wild blue yonder. Before they leap to attack prey or to travel to a new hunting ground, they tether themselves to a stationary object using a thread of silk called a "dragline" just in case they miss. The dragline allows them to reel themselves back to their launch site.
Jumping spiders commonly accidentally enter homes at this time of the year in search of prey. The spiders aren’t aggressive and even have entertainment value as you gently usher them from the premises. Their excellent eyesight makes them a bit jumpy, and they’ll commonly leap from whatever you’re using to move them outside. Of course, they also remain attached to their dragline and unless they land someplace, they’ll continue to rappel on what seems like a never-ending strand of silk.
Charlotte’s Web
Of course, we generally think of spiders as using silk to capture their prey. Web-producing spiders that are currently dominating (draping over?) landscapes in Ohio are Funnel Weavers (family Agelenidae); Sheet Weavers (family Linyphiidae); and Orb Weavers (family Araneidae).
The webs produced by funnel and sheet weavers commonly become more apparent once they become covered in dust after long dry spells. Heavy rains will not only wash away the dust but will sometimes destroy the webs.
Funnels of Fate
Funnel weavers produce large, flat, sheet-like webs spun across the grass, under rocks or boards, or over the branches of shrubs such as yews and junipers. Funnel webs may measure more than 1' across. The webs slope gently towards a narrow funnel or tube where the spider resides awaiting its next victim.
The medium-sized spiders resemble small wolf spiders. However, as with most spiders, they have excellent eyesight and will quickly scurry into their funnels if they spot arachnid-portrait photographers trying to snap a close-up (personal experience).
Sheets to Slaughter
Sheet weavers construct several types of webs depending on the spider species. Some species spin flat or slightly curved webs that overlay vegetation and rival the sizes of webs spun by funnel weavers. However, there is no funnel included in the web architecture. The spiders hide beneath one edge of the web, or inside plant foliage along the edge of the web, to await their prey.
One of the more interesting sheet weavers is the Bowl-and-Doily Weaver (Frontinella communis). This is one of the few spider species with males capable of producing webs; however, females still dominate web weaving.
The spider constructs a complex web structure consisting of distinctly bowl-shaped webbing suspended from plant stems by a crisscrossing array of silk threads; this is the "bowl" in the common name. The bowl is anchored below by a horizontal array of interwoven silk threads; the "doily." Flying insects drop into the web-bowl after bouncing in pinball fashion off the interlacing silk threads used to suspend the web. Of course, when they drop into the web-bowl, they fall into the "arms" (and fangs!) of the awaiting spider!
Orbs of Doom
Orb weaver spiders are the true spinmeisters of the spider world. They are so-named because of their circular, wheel-like webs. Their gossamer creations are most noticeable if cloaked in morning dew. Their webs are intricately engineered marvels involving both sticky silk to snare their food and non-sticky silk to provide structural support.
Non-sticky structural silk is used for "radial threads" which radiate from a central point like spokes on a bicycle wheel. The same type of silk is also used for "frame threads" which encircle the web like the rim of a bicycle wheel and for anchor lines that attach to static supports such as plant stems or buildings.
The spider starts at the frame threads and spirals towards the center of the web laying down a continuous line of sticky silk known as the “spiral thread.” It's the sticky spiral thread that snares the spider’s prey.
Some of the orb weavers construct webs where they can easily entangle the unwary. I call them the “in-your-face” spiders. They are typically medium to small-sized spiders but may appear much larger than life-sized when dangling just a few inches from your eyes.
Striking Arrows
One such in-your-face spider is the so-called Arrowhead Orbweaver (Verrucosa arenata). The "arrowhead" refers to its arrow-shaped abdomen and is very descriptive. The spider comes in bright red or muted brown color-forms with the “arrowhead” appearing to be covered in white or yellow cake frosting.
Arrowhead orbweavers commonly and inconveniently stretch their webs across forest trails. Their sticky webs are one reason it’s never a good idea to lead the way when hiking with others: it’s best to be second or third in line. I recently had a run-in (literally!) with this dime-sized spider and learned that I could still hit some high vocal notes. Thankfully, I was hiking alone. It was a repeat lesson in the value of using a “spider stick” to clear the trail ahead.
Arboreal Eye-Catcher
Another “in-your-face” spider is the so-called Arboreal Orbweaver (Neoscona crucifera). Spiders in the genus are sometimes called “spotted orbweavers” owing to spots on the undersides of their abdomen that some describe as looking like two broken “L’s.”
Research has shown that arboreal orbweavers prefer to position their webs in lighted areas to take advantage of the light attracting prey. They are commonly found near porch lights.
Young arboreal orbweavers are nocturnal and behave like a tiny Penelope in Greek mythology. They spin their webs in the evening and consume their webs in the morning. Mature females are found on their webs throughout the day. However, they will quickly flee their webs when disturbed often “ziplining” down a non-sticky anchor thread.
Their habit of positing webs near porch lights but not becoming apparent until the females are fully mature means these spiders may “suddenly appear” in some inconvenient spaces such as across doorways. Although the spiders are only around 1/2 – 3/4” from the tips of their legs, they appear much larger when you open an exit door and find one dangling in front of your face.
Trash-Talk
You need to peer into vegetation to spot the handiwork of Trashline Orbweavers (Cyclosa spp.). These tiny spiders stretch their webs between the branch tips of shrubs.
The spiders rest in the middle of their webs with a peculiar-looking structure made of dense webbing extending outward from the center of the web. Such structures of dense webbing are called a stabilimentum (plural stabilimenta).
The stabilimentum of trashline spiders is called a “detritus stabilimentum” because the silk enshrouds the drained bodies of previous victims as well as the molted exoskeletons of the spider. This morbid structure is responsible for the "trashline" common name.
The trashline spiders small size and mottled coloration make them difficult to spot among their similarly sized and colored bundles of trash. Indeed, research has shown that the trash bundles serve to confuse predators, such as birds and wasps, intent on making a meal of the spider, and the greater the number of bundles, the greater the confusion.
The Lack of Giants in the Weeds
Two of the largest-sized orb weavers found in Ohio are the Yellow Garden Spider (Argiope aurantia) and its equally showy cousin, the Whitebacked Garden Spider (A. trifasciata). Both spiders have multiple common names including zig-zag spiders owing to the pattern of their conspicuous stabilimenta.
These spiders are normally common in open fields, prairie plantings, and naturalized areas in Ohio. However, from my perspective, they’ve been conspicuous by their absence this season in the southwest part of our state.
I photographed an immature yellow garden spider earlier this season hidden behind her stabilimentum, but have not found mature spiders despite some focused searches. Of course, my observation, or lack thereof, has been less than scientific. Perhaps I’ve just failed to look in the right places, or my failure to locate mature females is simply due to naturally rising and falling population densities which is something I’ve suspected in the past.