Of over 45,000 species of spider worldwide, roughly 500 species live in the Kansas City area. It is estimated that over 11,000 spiders live in a typical acre of forestland. If that sounds like a lot, consider that the estimate for spiders in an acre of grassland is over two million.
It’s not all bad news, though. Many spiders will consume at least one insect per day. The overall impact of this predation is enormous. Think of how many pests we encounter regularly and then imagine not having the millions of eight-legged exterminators out there. Also, while almost all spiders are technically venomous, very few pose a threat to humans. In the Kansas City area, there are only two: the black widow and the brown recluse.
Female black widows have a glossy, black body and a large, round abdomen with two red triangles in an hourglass figure on the underside. In the southern widow, the triangles are connected and there are no other markings present. In the northern widow, the triangles are disconnected, there is usually a row of red spots along the top of the abdomen and there may be diagonal white markings on the sides. Males of both species are smaller and have different markings. Only the female has a medically significant bite and as trappers, they rarely move from the web. A black widow bite will often go unnoticed until later when localized pain sets in.
Brown recluses are generally a grayish yellow-brown with gray hairs on their oblong abdomen. The legs are darker brown than the body and are long and slender. They have a violin-shaped marking on the back of the “head” which gives this spider its other nickname: the violin spider. Females are larger than males, which is typical of spiders. As pursuit predators, recluses are usually seen walking or running as opposed to spending time on a web. Like the black widow, the bite may result in delayed pain.
Medical attention should be sought quickly if a bite is suspected and bite sites should be kept clean. Fortunately, the preferred defense is to run, rather than bite. Steps can be taken to avoid bites from these spiders. Both species are unlikely to remain in areas with regular activity, so use caution in uninhabited areas such as outbuildings, storage areas or seldom-used cabins. Always look carefully before reaching into things like boxes, log piles, clothes or even beds that have been in storage or have gone unused for extended periods of time. Minimizing clutter can reduce harborage and frequent activity such as vacuuming, dusting and sorting can render a space unattractive to spiders.
Though they may induce fear, brown recluses and black widows are relatively uncommon. You’re much more likely to encounter a grass spider, wolf spider, jumping spider, false widow or one of dozens of species of orb weaver spiders. All of these spiders are harmless to humans and are voracious beneficial predators. If an intolerable population of any spider infests the home, however, professionals should be called in to address the situation.
By Alex McCurter