It’s hard to believe that anyone wouldn’t love a black and yellow argiope spider (Argiope aurantia), even arachnophobes. With its bright markings, it’s arguably the most spectacular spider in North America.
Last year I wrote about barn spiders, in the same orb-weaver family, that had taken up residence around the exterior of my house in late summer. While I had plenty of barn spiders last year, I’d never seen an Argiope aurantia in the piedmont or mountains of Virginia, although they are common here. A large, tiger-colored, non-hairy spider, this species has attracted my attention over the many summer vacations I’ve spent at the Outer Banks of North Carolina.
This week I got lucky. I spied one making her web under my deck, anchoring it to the edge of the deck floor and the post that holds up the deck.
Also known as the black and yellow garden spider, the writing spider or corn spider, the black and yellow argiope belongs to a huge family (Araneidae) of approximately 3,500 species worldwide, with many species common to the United States. A. aurantia ranges throughout much of temperate North America, from southern Canada through most of the lower 48 states, and south through Mexico to Costa Rica.
Not all orb weavers are as gorgeous as this Argiope, but few are ugly as spiders go. Of course, I’m speaking as an arachnophile with a soft spot for this particular family.
The spider under my deck is relatively small, with a body about a half-inch long, so is likely one of this year’s new crop. Mature females, which are typically three to four times bigger than males and have a rounder body, can exceed one inch. Factor in the legs, and the largest of the species can span three inches or more.
Besides the striking markings that give it its name, the black and yellow argiope has orange or yellow bands on its long legs. And like other orb weavers, it has three claws per foot, one more than most spiders, according to Animal Diversity Web (animaldiversity.ummz.umich.edu), which says the spider uses this third claw to help manipulate the threads while spinning.
The Fairfax County Public Schools website (www.fcps.edu), which is a great source for nature information written in nontechnical language, explains how this species reproduces: After mating, the female spider lays up to a thousand eggs on one side of the web, then covers it with a papery sac that’s up to one inch wide. She then dies. The baby spiders hatch from their eggs in the fall, but they stay inside the sac through winter. In the spring, the young spiders leave the sac and go off on their own.
Orb weavers, as the name implies, make the roundish webs of concentric circles that are what most humans visualize when they think about spider webs. According to BugGuide.net, adult A. aurantia typically make a vertical zigzag band above and below the middle of the reinforced area of the web – the stabilimentum. Young females spin round stabilimentum, and males, when present, build a smaller web on the outer part of the female’s consisting of just a thick zigzag of white silk.
Black and yellow argiope tend to build their webs among flowers, shrubs and tall plants in sunny places sheltered from the wind, including gardens and fields, and around buildings. Like other orb weavers, each night they eat their webs and build new ones the next day.
Also in line with most orb weavers, this species preys predominantly on flying insects that get caught in its web, including mosquitoes, moths, flies, grasshoppers, aphids, bees and wasps. Even some small vertebrates, like lizards, can end up as prey if they happen to get entangled.
While its vision is poor, A. aurantia is very sensitive to vibrations in its web. Once a victim lands in it, the spider injects it with venom and wraps it up for later consumption. The venom not only immobilizes the prey but also starts to break down the contents of its body, making it easier for the spider to ingest. The use of venom is common to orb weavers. Those in the Argiope genus are non-aggressive, so they’re unlikely to bite except if handled. Even then, the consequences for humans are likely to be nothing more than brief local pain and itching, since the venom is very weak.
Predators of the black and yellow argiope include wasps (especially mud daubers), shrews and lizards. I’ve seen a ton of five-lined skinks this summer all around the outside of the house, so my orb weavers will have to be on their toes, so to speak.