OFFICE OF MONTGOMERY COUNTY
9020 Airport Rd
Conroe, TX 77303
(936) 539-7822 phone
(936) 788-8394 fax
mpotter@ag.tamu.edu
NEWS RELEASE
BY MICHAEL W. POTTER
County Extension Agent – Horticulture
June 8, 2024
Environmental conditions play a big part in plant problems and insect infestations. From year to year, weather patterns dictate the severity of insect problems. This year has been no exception. We have had a resurgence of the eastern tent caterpillars (Malacosoma Americanum) around the area. We have been inundated with concerns that trees will die. That is not the case and the damage will only be brief in most cases. The tree will likely be unsightly for the remainder of the season. However, in many scenarios leaves will begin to regrow.
I have witnessed a seen infestations of eastern tent caterpillars around our area and in our demonstration garden here at the office. There are four different tent caterpillars that frequent Texas: Eastern & Western, Forest and Sonoran tent caterpillars). They are distinguished in the larval stage by the following characteristics according to publication E-218 Tent Caterpillars:
- Eastern tent caterpillar has a solid white line down the center of its back.
- Forest tent caterpillar has a row of “keyhole” or “boot print” white marks along the center of its back, one on each body part or segment.
- Western tent caterpillars may sport a variety of markings and colors, but there is always a series of white dashes down the middle of the back.
- Sonoran tent caterpillar lacks white marks down the middle of the back, but it has a series of yellow dashes and blue spots on each segment. Also, the third from the last abdominal segment is mostly black on the top surface.
Caterpillars are larval stages of moths and butterflies and feed on the foliage of trees, shrubs, weeds, etc. You will often notice little pellets (poop) on the car, sidewalk or driveway when they are actively feeding. Most of the time we notice the “tent” (pocket of webbing) that they use to protect themselves from predators. One alternative is to break open the webbing to allow predators to have a feast. We have a Possumhaw Holly in our demonstration gardens that has been severely overcome by the larvae. Almost the entire tree is covered with webbing. We used a rake and broom to break open the webbing. Within minutes, predatory wasp and birds began swooping in and feeding on the exposed larvae.
If plants or trees begin to lose leaves; become bare or thin out excessively you may want to apply a natural pesticide like Bacillus thuringiensis (Bt). Leaves need to be thoroughly coated and the product must be re-applied after several days of direct sunlight or after a rain event occurs. The product only works if treated leaves are ingested by the feeding larva. It is always important to apply the product according to the label. Be careful not to spray or apply Bt to butterfly host plants.
Severe infestations may require a contact insecticide containing; permethrin, lambda- cyhalothrin, cyfluthrin, bifenthrin, fluvalinate, esfenvalerate, carbaryl, acephate or malathion. Just remember to read the label for application instructions. Also, when using contact insecticides, be sure to spray on days when winds are below 8 mph. This will help protect fish ponds or streams, other aquatic organisms and not to mention pets and neighbors.
Don’t forget to send your garden questions to Plant Answers at 9020 Airport Rd., Conroe TX 77303 or e-mail me at mpotter@ag.tamu.edu.
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.
The Texas A&M University System, U.S. Department of Agriculture, and the County Commissioners Courts of Texas Cooperating