By Austin M. Frishman, Ph.D.
Scorpions have successfully roamed this earth for some 400 million years — slightly longer than cockroaches have. They walk around with their tail (stinger) up in a curled position over their abdomen and large pedipalps (pinchers) in front of them, ready to grab a live meal. A scorpion sting can feel like a mild, wasp-like pinch. Unfortunately, some people are allergic to their venom and some species are more toxic than others. The smaller Arizona Centruroides genus packs a more potent sting than the larger desert hairy scorpion.
Scorpions are predators and nocturnal, which make them ideal candidates for glue boards and sticky traps, traditionally used for rodents. These devices can be used as monitors and population depressants, but monitors alone will not eliminate entire scorpion populations.
Reducing habitat harborage
Knowing that scorpions invade from the exterior, one of the most important things to do is reduce the number of harborage sites. This pest-proofing includes:
- Installing weather stripping around loose-fitting doors and windows.
- Making sure doors and crawlspace screens are tight-fitting.
- Repairing any tears in screening.
- Minimizing exterior trash, such as boards, logs and building material.
- Keeping vegetation from growing over the roof or touching the house.
- Scorpions are excellent climbers and will crawl up into plantings on trellises and fences. Lift flower pots and containers off the ground to thoroughly inspect those areas.
Scorpion weaknesses and pesticide applications
Scorpions glow under a black light (UV) and are strong nocturnal hunters. Use this type of light to look for them at night to help you pinpoint where to target your treatment.
Pesticides will not only kill scorpions crawling around at night, but also reduce insect populations that the scorpions feed upon. In areas with intense heat, pesticides can break down more rapidly, so it is important to select a formation that holds up better than an emulsifiable concentrate. Applying an exterior perimeter band 2-3 feet up the foundation wall will keep out most scorpions if they are invading from ground level.
Scorpion management process
Consider scorpion management a five-step process, as summarized in the National Pest Management Association Mobile Field Guide App:
- Inspect using a black/UV light at night.
- Eliminate exterior harborages.
- Reduce food (live insects) with appropriate pesticides.
- Take exclusionary efforts to ensure scorpions can’t enter structures.
- Apply a pesticide on the exterior and interior if the scorpion population pressure calls for it.
Here are some additional practical management tips:
- Continue to monitor with sticky traps.
- In very dry climates, scorpions will seek shelter where moisture accumulates. This can help you determine where to place the sticky traps, such as around condensers and evaporators of air conditioner units.
- Place outdoor lighting away from a structure - night lighting near a property draws insects in, which can then attract scorpions.
- Screen weep holes and other ventilation openings into a structure.
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