Fall Brings the Webworm

San Antonio Express News
Sunday, October 12, 2003

by Nathan Riggs

It doesn’t take much to look around and tell that autumn has arrived in South Texas. Mesquite trees have begun dropping their leaves, temperatures are mild, webworms are leaving the trees, fall gardens are in full force…the list goes on and on. Here at the Bexar County Extension office, our job is to educate and make the best better. This week’s article will answer some popular concerns voiced this week by local homeowners and pass along some helpful information as well.

Probably the most common phone call this week had something to do with webworms in some form or fashion. Most of the time, the question included the words “get rid of these webworms,” or “webworms are everywhere!…” or something similar. We have reached the time of year when webworms have finished eating and are ready to leave the tree to find a hibernation spot for the winter. Unfortunately, some homeowners are finding that the webworms are choosing their home for hibernation! To remedy this, treat a six to ten foot band around the foundation of the home (including patios and sheds), and treat the trunk of all pecan trees as well as under the trees to reduce the number of surviving caterpillars. A spray approved for pecan trees containing permethrin or pyrethrins should do the trick. It is not too late to tear open webs within reach which allows wasps, yellowjackets and birds access to the webworms inside. Take advantage of these allies in your annual battle with webworms!

For those still trying to spray mesquite trees and kill them, the time has passed. Mesquite trees are dropping their leaves and leaf sprays will do nothing. The only treatments that will work now are basal stem treatments using a mixture of Remedy herbicide and diesel that are applied in a band around the lower trunk. This method is described in detail in Extension’s Brush Busters pamphlet.

Fall gardens are in full swing around the area and many folks are busy pulling weeds, flicking bugs and nurturing those plants to get the most from them. Watch for hornworms, cabbage loopers and armyworms in your fall garden. These can be removed by careful hand picking or with an organic product containing the target-specific toxin Bt. Bt, or Bacillus thuringiensis, only kills caterpillars that eat its toxic crystals but leaves other insects and animals unharmed. Bt comes in liquid or dust formulations under many product lines. Follow labeled instructions and there should be no problems.

Although we say it quite often, it is important to protect yourself from mosquito bites during your outdoor time. Be sure to wear light-colored clothing (preferably long-sleeved) and consider using some sort of repellant. A few callers have asked about chiggers as well, and mosquito repellant applied to shoes, socks and lower pant legs will help repel those nasty biters!

Yellowjackets are still active, so be mindful of rock walls, ground covers and large bunch grasses such as Pampas Grass. These areas are favorite nesting sites for these small bee-like hornets. Treat nest openings at night with two teaspoons of any dust insecticide for success.

Fall is a wonderful time of year in South Texas with a myriad of outdoor activity choices. With a bit of awareness and a lot of creativity and initiative, your autumn can be as colorful as falling leaves and fulfilling as a plentiful harvest.

Nathan Riggs is an entomologist and Extension Agent-IPM with Texas Cooperative Extension in Bexar County. For more information call (210) 467-6575


Comments are closed.