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Common Types of Spiders in Missouri
Spiders are most closely related to scorpions, ticks and mites. Spiders have a body composed of two regions called the cephalothorax (head) and abdomen (body). They have eight legs, no antennae or wings, and an unsegmented abdomen. Four, six or eight eyes are located at the front of the cephalothorax. Also located at the front of the cephalothorax are the pedipalps, appendages used for handling food. (See above.) Spinnerets are located on the posterior tip of the abdomen. These structures are used to produce silk. Silk is used by spiders to make webs, construct egg sacs, line nests, wrap captured prey, or construct "balloons" with which to travel on air currents over large distances.
More than 300 different spiders occur in Missouri. Some of the more common groups include orb weavers, crab spiders, jumping spiders and wolf spiders. These groups are distinguished by the size and shape of their bodies, the structure of the legs and other appendages, and the size and relative position of the eyes. Tarantulas are not very abundant in Missouri but are occasionally collected from the southern part of the state. The brown recluse spider and black widow spider are the only two spiders in Missouri that are considered to be serious threats to human health. Most other species are considered nuisance pests when found in and around homes.
People tend to fear spiders because they believe that spiders are aggressive and seek to bite humans. This is an unfounded fear. While it is true that spiders will rush across their webs to investigate a vibration, this is just a natural hunting reaction to disturbance and should not be interpreted as aggressive behavior. Spiders do not attack and bite humans unless they are threatened or provoked in some way.
When a spider bite occurs, the victim is often unaware that it happened. Serious injuries or fatalities from spider bites are extremely rare. Very few spider species are considered to be a threat to human health, but the bite of the black widow or brown recluse spider can be serious. The reaction to a bite from these spiders can range from mild to severe, depending on the individual that is bitten and the amount of venom injected. The amount of venom injected varies from almost none to a full dose, depending on the quantity of venom in reserve at the time of biting, the length of time the fangs are in the tissue and even the location of the bite. Additionally, the reaction of different individuals to the same amount and type of venom will vary widely.
The female black widow is jet black with a red hourglass-shaped marking on the underside of the abdomen.
The black widow lives in undisturbed locations under trash, litter, boards and rocks. Little-used buildings may be infested as well as crawl spaces, cellars and basements. These spiders construct an irregular web in spaces between objects. They typically do not leave the web.
Bites usually occur when humans come into direct contact with the web or when the spider is unknowingly pinned against their skin.
The poison of the black widow spider affects nervous system function. The bite causes severe pain in the vicinity of the bite, accompanied later by dizziness, nausea, blurred vision and breathing difficulty.
The name "brown recluse" describes the color and habits of this spider. It is usually found in structures that contain dry, cluttered space that is undisturbed and has a supply of insects or other small organisms to serve as suitable prey. One study found this spider in about 70 percent of homes that were sampled in Missouri.
The color of the brown recluse varies from light tan to brown. The long neck of the fiddle points to the rear. A mature spider is about 1/2 inch long by 3/16 inch wide. Most encounters with brown recluse spiders occur at night when the spiders are active and foraging for food. During the day they are resting in secluded places. Other encounters occur when seldom-used clothes, containing a spider that has been using the garment as a hiding place, are worn.
Crab spiders are distinctive in body shape. All of the legs extend sideways from the cephalothorax. The first two pairs of legs are larger than the last two, which gives them a crablike appearance. They move about by walking sideways or backwards.
Crab spiders do not spin webs but capture their prey by ambush. Several species are brightly colored and wait for their prey on flowers. They are known to catch a variety of flies and bees that come to flowers collecting pollen.
They vary in size from medium to large, some species measuring 2 to 3 inches in diameter. Wolf spiders have long, stout legs — the fourth pair being the longest. The last two pairs of legs have longer hairs than the first two pairs.
Wolf spiders are found in a variety of habitats, usually near moist areas such as leaf litter, low-growing vegetation, the edges of streams, ponds or rivers, and on sandbars. They are known to dig burrows or tunnel into natural cavities under objects. They actively stalk their prey during the night, preying on ground-dwelling insects and other spiders. Wolf spiders are known for their wandering habits, and it is not unusual to find some that have wandered indoors.
How To Keep Spiders Away From Your Home
Spiders are most likely to enter the home in the fall due to their search for a warm place to spend the winter.
There are several ways that you can help to get rid of and prevent spider problems in your home:
Remove noticeable webs
Fill in gaps in walls and under doors to deter entry
Remove sheltering sites like firewood piles and compost piles from near your home
Use lighting in a way that is less attractive to the insects that spiders feed on
DeProw's EasyGuard program can help you tackle the problem of spiders in your home in a safe, effective and professional way.