Spiders: identification and control
When most people think of spiders in the Midwest the first thing that always comes to mind is the brown recluse spider. No spider with the exception of the black widow strikes more fear in residents of Evansville, Owensboro and Paducah than the “ole fiddle back”. So, we will start there. Why are brown recluse spiders referred to as fiddle backs? Most brown recluse spiders are a light brown color. On the cephalothorax, the segment right behind the head, there is a marking that is darker than the surrounding area. That marking resembles an upside-down fiddle. Males are usually more active and will be caught readily in glueboards. The female however will have a lighter/ yellowish color to the abdomen and stay relatively close to a very small, disorganized web. A brown recluse is a relatively small spider that is not web dependent. Typically, they will range from the size of a nickel to the size of a quarter, legs included. Most brown recluse are found in dark and moist areas. Most brown recluse in the tri state area are found outdoors under discarded items, rocks, under leaf litter, under the bark of trees and in woodpiles. They are an ambush predator and do not rely on a web to capture prey. Their venom is very toxic to insects and contains cytotoxic enzymes which damage blood vessels and cell membranes. Recluses are not normally aggressive and do not seek out contact with humans or other mammals as a food source. Unfortunately, people still do get bitten and in about 10% percent of the cases the bite can be severe. This usually occurs when people put on clothing that the recluse has made a harborage point. A pair of shoes that has not been worn recently or a shirt or jacket in a closet are good areas for brown recluse to harbor.
Always check or shake out items of clothing before you put them on if you suspect that you might have an infestation of brown recluse spiders. Most people are not even aware that they have been bitten and the bite may create small irritation or itching. For the 10% that react violently to a bite the reaction can be very serious. For some, the bite will become very red and resemble a target with a bullseye in the middle. Some of the bites will advance beyond this redness and necrosis may occur. Necrosis is the premature death of skin and cells that occurs when the skin comes in contact severe infections, trauma or introduced toxins. The affected area can’t be cured must be removed via medication or surgery. In very severe cases plastic surgery is required to reduce the unsightliness of the scar. The most effective way to combat brown recluse infestation is a good exclusion protocol on the exterior to stop spiders from entering to overwinter. Common entry points are around doors, windows, soffits, vent, pipe openings and crawl space doors. Glue boards are very effective in reducing the male population and monitoring the existing populations but a more in-depth treatment including regular vacuuming may be needed in larger populations. In very severe infestations fumigation may be necessary to eliminate the issue.
Another common spider that many residents in Paducah, Evansville and Owensboro may encounter is the black widow spider. Black widow spiders are a web dependent arachnid and use their web to capture prey. They build small unorganized webs in dark areas. Typically they will be found underneath brick ledges, soffits, woodpiles and building foundations. The males are lighter in color and much smaller than the females. The most identifying characteristic of the female is a bright red hourglass marking on the underside of the abdomen. Sometimes the female will consume the male after reproduction thus the name “black widow”. The female is about the size of a dime to nickel with the legs included. Black widows are a very shy spider. They do not typically seek out contact with others unless their harborage point is disturbed or protecting their egg sacs. Although the males can bite their venom is not of concerns to humans. Black widows venom contain latrotoxin which is a strong neurotoxin that affects the nervous system. The bite can cause serious distress, muscle cramps and excessive sweating. Although the bites are very uncomfortable serious illness or hospitalizations are rare. Control can be achieved by eliminating their harborage points and residual insecticides to keep their population at bay.
Another very common spider that manner people confuse with the brown recluse spider is the wolf spider. The wolf spider is a dark spider that resembles the brown recluse slightly. Wolf spiders are around the same size as the brown recluse but are stockier and have a “hairy” appearance. On the cephalothorax they have two black bands with a brown line in the middle. Like the brown recluse spider it also does not use a web to capture its prey. It is an ambush predator and hunts other insects as well as the brown recluse spider. Many people ask the best way to control them and my answer is that control can be achieved in the same manner we control other spider species. However, wolf spiders are usually place in the beneficial category as they act as “normal” pest control. Fortunately, their bite is not toxic and usually mild in nature.
The common house spider is another arachnid that you will commonly encounter in the Evansville, Paducah and Owensboro area. House spiders are the main reason for the many cobwebs we see in our homes. They are a very small spider, usually smaller than a dime including their legs. These spiders typically build their webs in the corner of walls, windows and door openings. They prefer dark moist areas like basement and crawlspaces away from disturbance. House spiders typically abandon most of the webs to build new ones which makes an infestation appear more severe than it actually is. The house spider is not aggressive and its bite is not harmful to humans. Although a beneficial spider due to its nature to prey on other insects it can be quite annoying with its excessive web building.
