Fall is the season for spider encounters in Utah. Many are nearing the end of their lives and are searching for mates and laying eggs. These habits can increase the chance of human-spider interactions. Below are descriptions of spiders commonly encountered in the fall in Utah.
• The hobo spider is the spider most seen in the fall. Populations are large in northern Utah, and when male spiders leave their webs in search of mates, they often find their way indoors. The Utah State University Extension Utah Plant Pest Diagnostic Lab recently created a website to address questions about hobos at https://utahpests.usu.edu/uppdl/hobo-spiders.
• Wolf spiders are ground hunters and pursue prey in lawns and gardens. They do not spend much time in webs. In the fall, females have their egg sacs attached to the rear of their body (spinnerets). When the eggs hatch, small spiderlings climb up on the mother’s abdomen and stay there for about a week before dispersing. Large spiders in the genus Hogna cause particular concern this time of year, but like all wolf spiders, they are not poisonous to humans.
• The banded orb-weaving spider and cat-face spider are two interesting looking spiders that Utahns might encounter. The adult female banded orb-weaver has a large, oval-shaped abdomen adorned with black, yellow and white stripes and black bands on the legs. The cat-face female has a large, oddly shaped abdomen that resembles the face of a cat when viewed from the proper angle. Cat-face spiders are attracted to porch lights where their perfectly shaped orb webs pluck flying insects from the air. This time of year, females sometimes wander inside homes or other enclosures in search of an egg-laying site. Once eggs are laid, females will likely die. The eggs will hatch next spring, and spiderlings will climb structures and plants, release long strands of silk and “balloon” away in the wind to new sites.
• The golden huntsman (giant crab spider) is the most common huntsman spider identified by the UPPDL. These large spiders are gold in color with black mouthparts and dense black hairs on the end of their legs, giving the appearance of dark socks. These “socks” allow the spider to climb up almost any surface. They are commonly found under the bark of trees or in narrow, secluded places.
• The tarantula can be found as far north as Cache County, but Utah is on the northern border of its native range. In the fall, male tarantulas leave their underground burrows and migrate in search of female mates, sometimes into home landscapes. The genus of tarantula found in Utah is not harmful to humans.
None of the above spiders should be feared. The influx of spiders usually ends in late October, and tolerance of these beneficial creatures is the ideal strategy. For additional information and control techniques, visit http://utahpests.usu.edu/.
By: Ryan Davis - Oct. 18, 2011