Scorpions
Fact Sheet No. 68
Dr. Jay B. Karren, Extension Entomologist
Revised October 2001 Alan H. Roe, Insect Diagnostician
Introduction
Scorpions belong to a small order of insect-like animals from the class Arachnida, which
includes ticks, spiders, and mites. Of approximately 75 species that are found in the United
States, only nine species are recognized from Utah. Most species of scorpions are found in
the Southwest; therefore, most of the Utah species are found in the southern part of the state.
Individual specimens are usually found in the more semi-arid desert regions of the southern
half of Utah. Three species are occasionally collected in northern Utah.
Scorpions do not bite but inflict a sting by means of a stinger at the end of the tail. Although
they are usually depicted as menacing creatures with a deadly sting, in the United States
most species of scorpions are non-lethal.
Only one U.S. species is considered to possess a life threatening sting. Centruroides
exilicauda Wood (also known as C. sculpturatus), is found abundantly in Southern Arizona,
Texas, New Mexico, and Southern California. Two specimens have been collected from
Hole-in-the-Rock in Kane County, Utah. This more poisonous species is commonly called
the sculptured or bark scorpion because of its association with trees. It can be found hiding
under bark on firewood and wooden fence posts around homes. It is comparatively small,
yellowish or straw-colored with small, slender pincers. Although the sting of this scorpion
can be deadly, stings by most other species of scorpions are not particularly serious and
usually result only in localized pain, with some swelling and tenderness.

Description and Habitat

Scorpions are easily recognized by their lobster-like appearance and their fleshy, tail-like
post-abdomen which ends in a bulbous sac and prominent sting. They have four pairs of legs
and a combined head and thorax, called a cephalothorax. A front pair of leg-like appendages
are enlarged and equipped at the terminal end with pincers, much like those of a crab or
crayfish. Scorpions vary in color from black, gray, brown, and yellow. They are from 1/2 to
7 1/4 inches long.
Scorpions are most active at night. They never burrow but may hide under boards, rubbish,
bricks, etc., which provide shelter and may harbor the soft- bodied insects and spiders that
scorpions feed upon. The scorpion's body is flattened and depressed because of the habit of
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living under stones and in cracks and crevices. This enables them to enter homes from
outdoors through very small openings of less than one-eighth of an inch. Generally, they are
found under the house or in the attic. They may be found in washrooms, kitchens, or
bathrooms where water is available and in the daytime hide in closets, shoes, folded blankets,
etc. Fortunately, scorpions are seldom found in houses except those in recently developed
desert areas.
Scorpions should be considered transient pests that will most likely leave at the first chance,
since little prey is available indoors and the average house temperature is not comfortable for
them. Outside they are frequently found burrowing into children's sand boxes, ditches, gravel
banks, under firewood or other objects in the yard. Scorpions seldom sting humans--only
when handled or provoked. Few species worldwide are considered deadly (only the one
mentioned above is found in the United States). However, scorpions are common in some
areas and all should be considered dangerous.

Life Cycle

Scorpions have a long life cycle--two to five years. They usually mate in the fall or early
spring after an elaborate courtship dance that may last several hours. During the dance, their
tails become entwined and the male leads the female by means of her chelicerae to a
protected area where, without releasing her, he digs a hole into which they retire. After
mating, the female often eats the male. Scorpions do not lay eggs; the female bears live
young 7-12 months after mating. A female may produce from 14 to more than 100 young in
a litter, depending on the species. After birth, the young scorpions climb on the back of the
mother and remain, fastened by their pincers, until after the first molt, when they leave the
mother to fend for themselves. The immatures molt several times until they reach maturity in
about one year. Scorpions are canniba-listic and will readily eat other species and smaller
individuals of their own species, and the mother will even eat her own young.

Utah Species
Scientific Name
Distribution
Size
Anuroctonus
phaeodactylus
Great Basin
Large
Centruroides exilicauda
Kane County
Medium-sized
Hadrurus arizonensis
Southwestern
Utah
Large (100 mm)
Hadrurus spadix
Southeastern Utah
Large (100 mm)
Vejovis becki
Washington
County
Medium-sized
Vejovis boreus
All of Utah
Medium-sized
Vejovis confusus
Western Utah
Medium-sized
Vejovis wupatkiensis Southeastern Utah
Small
Vejovis utahensis
Southeastern Utah
Medium-sized
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Habits and Feeding Behavior

Scorpions are secretive and usually spend the daylight hours hidden under or in objects on
the ground. At night they emerge hunt for prey and feed. Burrowing species may sit
motionless at or beside the burrow entrance waiting for contact with wandering prey.

Scorpions should be considered beneficial predators since they feed on a wide variety of
insects, spiders, and other arthropods. Crustacea, such as sowbugs and hard-bodied insects
are usually rejected. On rare occasions, the larger species may attack small, immature
vertebrates, such as lizards and snakes. Prey is attacked by thrusting the tail and embedding
the sting into the victim. Some venom is also forced into the puncture wound. When the prey
has been subdued, the scorpion only ingests the body fluids of its victim. Tiny bits of food
are torn off by the claw-like chelicerae and placed into the pre-oral cavity. Digestive juices
flow onto and pre-digest these pieces which are then sucked into the stomach. Indigestible
particles are discarded.

Scorpion Stings

Most ground scorpions inject a venom that destroys red blood cells. It produces a localized
discoloration at the site of the sting and painful swelling of the area. However, a sting from a
Centruroides species causes very little swelling or discoloration and should be treated by a
doc-tor. Children and elderly people are especially vulnerable to this venom. Systemic
reactions to this neurotoxic venom include restlessness, convulsions, staggering gait, thick
tongue sensation, slurred speech, drooling, excessive sensitivity of skin, muscle twitches,
abdominal pain and cramps, and respiratory depression. These symptoms usually subside
within 48 hours.

Treatment of Scorpion Stings

In most cases, treatment of scorpion stings in the United States is done to relieve the
symptoms. There are no first aid measures of real value in the treatment of scorpion stings
and an individual's reaction to the venom can vary greatly. The following should be
observed:
1. Contact a physician or poison control center for instructions.
2. Placing a piece of ice over the wound site may reduce pain.
3. Do not submerge the affected limb in ice water.
4. Do not make any incision at the site of the sting.
5. Keep the victim relaxed and calm.
6. Victim should not consume alcoholic beverages or take sedatives.
7. Capture the scorpion for identification if possible.

Control


Controlling scorpions is difficult, if not impossible, even for the professional pest control
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operator. During dry weather, scorpions can be trapped by spreading wet burlap bags around
buildings. Firewood, stones, lumber, and other debris should also be removed from the
vicinity. Gloves and protective clothing should be worn when cleaning up areas where
scorpions may hide. Tight doors and window seals will help keep scorpions out of the house.

Outdoor applications of residual pesticides are aimed at eliminating scorpions from the
immediate area (before they gain entry into the home). Most general yard sprays will also
reduce prey populations that have served as food and will have some effect on reducing the
number of scorpions.
There are numerous formulations of insecticides labeled for scorpion control in indoor and
outdoor situations around the home. Some of these are restricted to use outdoors, but many
can be used in either situation. Products labeled for this purpose include many dust
formulations of bendiocarb and deltamethrin, numerous ready-to-use solutions or
pressurized-liquids containing allethrin, bifenthrin, chlorpyrifos, diazinon, permethrin,
prallethrin, propoxur, pyrethrins, tralomethrin, or tetramethrin. Some water-soluble and
emulsifiable formulations of carbaryl or cyfluthrin (mostly for outdoors), or esfenvalerate are
also labeled. Some microencapsulated formulations of chlorpyrifos, diazinon, and pyrethrins
are labeled for scorpion control, but most are formulations intended for commercial
applicators.
Hiding places should be located and treated, and any scorpions that are observed can be
treated directly. Repeated applications may be necessary for effective control since scorpions
may hide for two to three months after feeding. Refer to the specific product label for
application rates, sites, and precautions for any insecticides you might apply.

Precautionary Statement


All pesticides have both benefits and risks. Benefits can be maximized and risks minimized
by reading and following the labeling. Pay close attention to the directions for use and the
precautionary statements. The information on pesticide labels contains both instructions and
limitations. Pesticide labels are legal documents, and it is a violation of both federal and state
laws to use a pesticide inconsistent with its labeling. The pesticide applicator is legally
responsible for proper use. Always read and follow the label.

References
Ennik, F. 1972. A Short Review of Scorpion Biology, Management of Stings, and Control.
Calif. Vector News
Johnson, J.D. and D. M. Allred. 1972. Scorpions of Utah. Great Basin Naturalist 32(3):153-
170.
National Pest Control Association. 1985. Scorpions. Technical Release ESPC 036501A.
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