Southern House Spider, Kukulcania hibernalis

The Southern House Spider (Kukulcania hibernalis) is a species of large North American spider which display strong sexual dimorphism. The males may be mistaken for the Brown Recluse due to the similar coloration and body structure. However, compared to the Brown Recluse, male Southern House Spiders are usually larger in size, lack the distinctive violin shape on their cephalothorax, and have abnormally long and slender pedipalps. The females are a dark brown or black color and more compact. Both male and female may grow to be about 2 inches across, with the males typically having longer legs, and the females often having larger, bulbous bodies. The abdomen of this spider is covered with fine velvety light gray colored hair.

The female individuals of this species are rarely seen, as they built radial webs around crevices, for which reason their family, Filistatidae, is called crevice weavers. The females rarely move except to capture prey caught in their webs. The males, on the other hand, typically wander in search of insects and females to mate with, having no particular territory.

This spider is a cribellate spider, meaning, its spinnerets don’t produce adhesive webbing. Instead, to capture their prey, the spider uses its legs to comb webbing across its cribellum, a spiked plate by the spinnerets. This combing action frays and tangles the strands, making a fine velcro-like netting that traps insect legs.

The male individuals occasionally appear aggressive, but they don’t bite unless they are trapped, and their mouthparts are too small to easily penetrate human skin. They do, however, have an unsettling tendency to crawl across anything in their path regardless of whether it is alive. This is not aggression; these spiders are almost entirely blind and cannot see larger animals. Indeed, these spiders instinctively play dead if they feel threatened. They are capable of crawling through crevices as narrow as ¼ of an inch because of their elongated bodies and compact legs.

The mating ritual is a lengthy and elaborate process with long periods during which neither sex moves considerably. When the wandering male encounters a female’s web, there may be an initial confrontation where each scares the other. Upon recovering, the male individual then builds a large web around the females crevice. When this web is finished, the male pulls on its strands continuously to draw the female out of her hole, which may take up to several minutes. Following her emergence, each spider will tap at the other in an effort to grasp the other by the forelegs, with the male staying suspended in his web.

Image Caption: Kukulcania hibernalis at Congaree National Park, South Carolina, USA. Credit: Theresa Thom/Wikipedia