Watch Out for Scorpions in Summer!!!

Nathan Riggs, Extension Agent - IPM

Texas Cooperative Extension, Bexar County

Summer in San Antonio means heat and markedly less rainfall than other times of the year. This week's article from the Bexar County Extension Office will talk about ways to control scorpions around homes.

Late May and the entire month of June mark the most active time of the year for scorpions in San Antonio and South Texas. There are two species of scorpions found in Bexar County: the Striped Bark Scorpion (Centruroides vittatus) and another unnamed scorpion (Vaejovis reddelli). Neither of these scorpions is considered deadly poisonous to most people unless there are allergic sensitivities to stings.

The striped bark scorpion (photo at left by N. Riggs) prefers rocky or brushy areas or homes to hide in and hunt for their prey. They are tan to brown with darker stripes running the length of their back and average 2 ½ inches in length. Their claws are very thin and light in color.The Vaejovis scorpion (photo at right, not credited) is much darker - reddish brown to almost a black-brown color - with much larger claws, and averages only two inches in length. This scorpion is common in caves and in leaf litter associated with live oak trees.

Both of these scorpions feed on insects, small centipedes and other scorpions. They prefer to hunt at night and remain hidden during the day to conserve water and avoid high temperatures. Baby scorpions are born alive after a long gestation and will remain on their mother's back for approximately 7 to 10 days until they shed their skin, or molt, the first time. After molting, the baby scorpions leave the safety of their mother's back to live their lives alone.

What can be done to keep scorpions outdoors and not indoors? There are a few simple tricks that one can try to accomplish this. For brick or rock homes, place pieces of rolled-up nylon scrubbing pad into the weep holes around the bottom of the outside of the home. This will allow air and moisture transfer in the walls while impeding the entry of the scorpions. For stucco homes, check the gap between the stucco and the concrete foundation of the home and consider some sort of approach for preventing scorpion entry into that area. Also be sure that weatherstripping around doors and windows is in good condition. Since scorpions feed on insects, it would be a feasible assumption to say that the insects around porch lights at night would attract scorpions. While this is true, one must remember that scorpions are generally not comfortable in lighted situations. Turning off the porch light would actually NOT repel scorpions. Another consideration for scorpions is brush, wood or rock piles near homes. These are perfect hiding and hunting places for scorpions. If these piles are not necessary, try to either remove them, or move them away from the home.

Chemical treatments for scorpions are many, but there are a few products on the market that seem to have better activity against scorpions than others. Look for sprays or granular products that contain one of the following active ingredients: permethrin, cyfluthrin, bifenthrin or deltamethrin. Products containing these active ingredients are sold at Wal Mart, Lowe's and Home Depot for sure, along with many local nurseries and feed stores as well. Liquids should be sprayed along the foundation of the home and 12 to 24 inches up the side of the exterior wall. Granules should be applied in a six to ten-foot band around the foundation of the home and then gently sprinkled with water to release the insecticide. Indoors, consider placing sticky traps (used for catching mice or rats) under or behind couches, sofas or beds and along baseboards where scorpions travel. You'll be surprised what gets caught on that trap!! For more information on scorpions, click on the link to the Field Guide to Common Texas Insects OR download a PDF file of Extension Publication L-1678 on Scorpions.

Portions of this article were originally published in the June 17, 2001 Extension Service article in the San Antonio Express News - Real Estate section.

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Updated: July 8, 2002