Creepy Critters

A lot of creepy critters are starting to show up in my neighborhood as Halloween approaches.  Many people are putting out scary pumpkins, bats, spiderwebs, and spiders.  There are about 3,000 species of real spiders in North America, and all spiders have fangs that inject venom used to paralyze or kill their prey.

Spiders are normally quite timid and must be threatened or provoked before they will attack a species larger than themselves.  All spiders will bite, but most species do not have teeth that are large enough to break human skin.  Of those that can bite through our skin, only four species dangerous to humans are found in North America.  They belong to two groups, the widow spiders with three species in North America and the recluse spiders with eleven species in North America.

Widow spiders are all commonly called black widows, but they are actually three different species located across North America and include the western species, Lactrodectus hesperus, the northern species, Lactrodectus variolus, and the southern species, Lactrodectus mactans.  In northern Illinois, the northern widow is a small species between 1/8″ and 3/8″ long.  Males have long abdomens with white and red markings while females have more rounded abdomens with a red hourglass marking on their underside.

Widow spiders are shy and tend to remain hidden under logs and stones, or just inside entrances to animal burrows.  During autumn, as temperatures drop, they will move inside if possible and are often encountered under furniture, boxes, or discarded items that are not often disturbed.  Webs are funnel-shaped and provide for adults and eggs.  Once eggs are laid, the female will rarely leave the eggs untended, and will aggressively protect them from all harm, attempting to bite anyone that disturbs her or the eggs.

Black widows tend to flee rather than bite, unless they are protecting eggs.  Only the females bite and their venom is especially dangerous to humans, but bites are not painful and may not even be noticeable at first.  Severe stomach cramping develops within an hour or two and breathing may become difficult.  Despite the uncomfortable effects, black widow bites are lethal in less than 1% of cases.

The brown recluse, Loxosceles reclusa, is the most widespread of the recluse spiders, and is often found in or around human dwellings.  Other recluse species are found in very limited areas.  Their favorite outdoor spots are under boards, stones and log piles, but they are most often found inside in quiet areas on the floor or behind furniture.  Adult spiders are a light yellow-brown with a dark violin-shaped marking on their back.  Adults are between 1/4″ and 1/2″ long with long, thin legs that can be three to four times the length of their body.

Recluse spiders are not aggressive and will only bite when disturbed.  Most bites occur when the spider is caught in an article of clothing that is picked up off the floor, startling the spider.  Once bitten, the wound develops a crust with a red zone around it.  The crust may fall off rather quickly but leaves a crater behind that may take several months to fully heal.  Although their bite may cause tissue damage, there have been no confirmed deaths in the United States.

Halloween is a special time of year and can be a fun time with scary creatures and other haunts.  The Juricha-Suchy Nature Museum is hosting its 13th annual Creepy Critters Halloween Open House on October 26th (for info, please call (630) 829-6546 or email JuricaSuchyMuseum@ben.edu).  I hope you get out for some trick-or-treating of your own, and let the real spiders live quietly in their own habitats.