SCOURGE OF THE SOUTHWEST

Scorpions are not insects, but rather they are arachnids with eight legs and a pair of long pedipalps ending in pincers resembling a lobster’s. But regardless of what family or class these eight-legged creatures belong to, they are still referred to as "pests" by customers when they are found inside a home or business. And, because scorpions are considered pests, a pest management professional must develop a strategic control plan should he or she receive a service request.

About 90 percent of scorpion species occur in the United States and, although they are mostly associated with the Southwest, scorpions can be found as far east as North Carolina. "Scorpions are more active in warm weather, so it makes sense that they are associated in areas that are warm all year long," said Dr. Mark Lacey, president of IPM-Network and an industry veteran with more than 20 years of pest control experience. Lacey spoke about scorpion control at the National Pest Management Association’s Pest Management 2000 in Las Vegas.

WHY CONTROL SCORPIONS? "Scorpions can be compared to spiders when spoken as a structural pest," Lacey said. "They don’t cause any damage to the home and they are actually beneficial because they feed on other insects."

In fact, some larger species of scorpions feed on mice, rats and snakes. "But most people don’t want scorpions in their home because — similar to spiders — there’s a fear factor involved with them," Lacey said.

Fear surrounding scorpions is mostly due to the fact that they sting when agitated. However, the venom of most scorpions is not dangerous and their sting is no more painful than that of a wasp. The bark scorpion, which is found primarily in southern Arizona and New Mexico, is considered the most dangerous species of scorpion in the U.S. The bark spider’s sting can be felt immediately and can pose serious danger to children and the elderly. In extreme cases, the venom of a bark scorpion may produce severe pain, swelling, numbness, difficulty breathing, muscle twitching and convulsions.

According to Lacey, many people think that the larger the scorpion, the more dangerous. The opposite is true. "As a rule of thumb, the thinner a scorpion’s pincers, the more venomous they tend to be," he said.

If a sting should occur from any scorpion species, pain and swelling are usually immediate and will be localized only in the area of the sting. Ice or cold water should be applied directly to the sting site until the pain subsides.

CAREFUL INSPECTION. The first step in controlling scorpions is an inspection to determine harborage sites. Around the home, scorpions hide under mulch and rocks, under or on tree trunks, in shrubs and under siding. Scorpions often find their way into homes and buildings by accident while hunting for food. They usually enter underneath door thresholds, but they can also enter through utility pipes and cracks, crevices or weep holes. "Scorpions hide in cool, dark places, so it is very unusual to see a scorpion out in the open during the day when temperatures are at their warmest," Lacey said.

Inside structures, scorpions hide in dark areas such as attics, crawlspaces, bathrooms, closets, shoes and blankets. Do scorpions infest homes? "As long as they have a food source they certainly can," Lacey said. "Scorpions are predators that feed on insects. Some species also feed on rodents and snakes. The presence of scorpions in a home is usually an indication there are other insects in the home they are feeding on."

According to Lacey, most scorpions are loners, however, bark scorpions tend to be colonial. "That means they are more likely to live in groups in close proximity to one another, therefore, they are the species most likely to infest a home."

And the presence of bark scorpions means that it is crucial for PCOs to protect themselves from scorpion stings while inspecting or treating a home or building by wearing heavy gloves, boots and long sleeves. "Don’t reach into anything with bare hands. Also, scorpions can sting through latex gloves and most clothing. But they can’t sting through tough materials such as leather or vinyl," Lacey said.

Scorpions are nocturnal and tend to be more active when temperatures are lower than 77°F; therefore, night inspections are effective. One of the most important tools to use for scorpion inspection is a flashlight or blacklight because a scorpion’s exoskeleton glows under the bulb. "However, a scorpion can see that bright light just as clearly as a PCO can, and it will usually run from it," Lacey said.

According to Lacey, another important tool to use is an inspection mirror because it allows the PCO to inspect small areas.

MANAGEMENT AND TREATMENT. The first step in managing a scorpion infestation is to remove potential harborages outside the building. This includes removing trash and debris, storing lumber off the ground, installing a barrier strip of gravel around the foundation and removing unnecessary rocks. "Unfortunately in the Southwest, people often have rocks in their yards in place of a lawn. In that case I usually recommend that the rocks be less than ¾-inch in diameter so the scorpion can’t hide under it," Lacey said.

Next, PCOs should recommend various IPM techniques, which may include caulking cracks and crevices, sealing the bottom of stucco walls and applying weather-stripping tape to doors and windows. When treating an area for scorpions, perimeter treatments are often necessary to provide quick relief from outdoor invasions. "A good formulation for a perimeter treatment is a microencapsulated or wettable powder," Lacey said.

For an indoor treatment, Lacey recommends using a dust that can be applied into outdoor cracks and crevices. It is also important to remember that scorpions are predators that hunt living prey. Therefore, removing other pests that serve as a food source for scorpions is the most important control measure.

CONCLUSION. Scorpions tend to enter homes and buildings while searching for food. It is important for PCOs to remember that scorpions will only infest a structure if it has a prominent food source. "By eliminating all food sources and using exclusion techniques, a PCO can develop an effective scorpion management program," Lacey said.

The author is Internet editor of www.pctonline.com and can be reached at apaskiet@pctonline.com.