Scorpions
Darryl P. Sanders
Department of Entomology
Scorpions make up a small order of arthropods most closely related to spiders. Scorpions have eight legs, a combined head and thorax called a cephalothorax, and a segmented abdomen. They have a pair of large pincerlike pedipalps at the front of their bodies, which they use for catching prey. Their abdomens are segmented with an elongated tail ending in a stinger, usually carried elevated up and over the body.
Scorpions feed on spiders and soft-bodied insects. Small prey may be eaten immediately, while larger prey are stung and then eaten after movement stops.
Scorpions hide during the day and are active at night. They tend to live under boards, stones, or other objects; or beneath loose bark on trees and logs. Indoors, they are most often found in crawl spaces and attics. During the summer they often enter houses. Although scorpions tend to be found on dry land, they require moisture and may be attracted to water sources. They generally do not like extremely high temperatures and may be driven to enter the living areas of a home seeking relief from heat and dryness. Scorpions survive well in terrariums and make interesting "pets."
Several species of scorpions are found in the United States, with most inhabiting areas in the South and Southwest. The only naturally occurring species in Missouri is the striped scorpion, Centruroides vittatus. Adult striped scorpions are yellowish tan with two broad, darkened longitudinal bands on the top of the abdomen. They are up to 2.5 inches long (illustration). The female produces living young, which she carries on her back for five to 15 days until they leave and become independent. It takes three to four years for the young to reach maturity. Adults may live two to five years.
Figure 1
Striped scorpion (Centruroides vittatus.)
Control measures
Boards, stones, wood piles and similar harborage sites should be removed from around the house. Firewood and lumber should be stored off the ground. During dry weather, scorpions may be attracted to wet burlap bags spread on the ground around the house and then killed by crushing with a heavy object. Eliminating insect populations from around the house helps because it removes the scorpion's food source. Caulking or other means of closing cracks under and around doors and windows is advised. Ducks and chickens maintained in the yard around a house will eliminate most scorpions.
Applying a barrier strip of residual pesticide around the house helps repel scorpions. Spray the ground from the foundation out about 10 feet and the foundation from the ground up about 2 feet. Particular attention should be paid to treating weep holes in brick veneer and around basement window wells. Use one of the following: bendiocarb (Ficam®), carbaryl (Sevin®), chlorpyrifos (Dursban®), cyfluthrin (Tempo®), deltamethrin (DeltaGard®), diazinon, permethrin (Prelude®) or propoxur (Baygon®). Follow label instructions.
Attics, wall voids and crawl spaces are best treated with a dust formulation of one of these pesticides. Residual sprays into cracks and crevices also help.
Scorpion stings
All scorpions have poison glands located in the bulbous last segment of the abdomen, which ends in the stinger. Scorpions rarely sting humans except when pinned against the skin. The sting of the striped scorpion usually results in a localized painful swelling and discoloration at the sting site. The effect lasts only for a few hours and has been described as being similar to a bee or wasp sting. There are other species of scorpions found only in southern Arizona and Mexico that have been responsible for human deaths.
G7364, reviewed March 1997