Spiders’ web-building habits often spark questions. Not all spiders, especially dangerous ones, build large, easily identifiable webs to catch prey. Spider behavior concerning silk use varies widely by species.
Not All Spiders Build Webs for Hunting
While all spiders produce silk, not every species uses it to build intricate webs for trapping food. Many spiders are active hunters, relying on speed, camouflage, or ambush tactics. These “wandering” or “hunting” spiders include wolf spiders, jumping spiders, and crab spiders.
These spiders utilize silk for purposes other than trapping prey, such as creating draglines for safety, constructing protective retreats, or forming egg sacs. For instance, a wolf spider actively pursues prey on the ground, while a jumping spider stalks and pounces on insects. Crab spiders often hide on flowers, ambushing unsuspecting prey.
Webs of Medically Significant Spiders
When considering spiders of medical concern, their web-building habits differ significantly. Black widow spiders, for example, are known for their distinctive webs. These are typically messy, irregular, and tangled, sometimes appearing funnel-shaped.
These webs are often found in dark, undisturbed locations like woodpiles, sheds, or under eaves. The silk of a black widow’s web is notably strong and sticky, effectively ensnaring insects.
In stark contrast, brown recluse spiders do not build organized hunting webs. They are primarily wandering hunters that construct small, irregular silken retreats in secluded areas. These loosely constructed webs are not designed to catch prey but serve as shelter or for egg sacs.
Their retreats are commonly found in dry, dark places such as attics, basements, closets, or within stored items.
Identifying Spiders Without Relying on Webs
Since not all spiders of concern build obvious trapping webs, identification relies on other clues. Observing their preferred habitats can be helpful, as many medically significant spiders favor dark, undisturbed environments.
Physical appearance provides key identifying features. Female black widow spiders are typically shiny black with a prominent red or orange hourglass marking on the underside of their abdomen. Brown recluse spiders, conversely, have a distinct dark brown violin-shaped marking on their cephalothorax, with the “neck” pointing towards their abdomen. Unlike most spiders with eight eyes, brown recluses have six eyes arranged in three pairs.
Behavioral cues also offer insights. Black widows are nocturnal and often hang upside down in their webs. Brown recluses are reclusive and nocturnal, emerging at night to hunt. If uncertainty arises about a spider’s identity or following a suspected bite, consulting a medical professional or a pest control expert is always advised.