"‘Cotton candy in the trees’" By Aaron Sumrall, PhD County Extension Agent Agriculture & Natural Resources

   Current conditions across Matagorda County are similar to conditions of August and September - so many questions I receive are typical of late summer. 
   The headline of this article is much like how the conversation begins in many of the calls with homeowners concerned about the “cotton candy-looking webs in the trees” or leaves being stripped. 
   The two primary culprits initiating the calls and concerns are Fall Webworm or Walnut Caterpillar. Let’s discuss the two and point out a few factors and considerations to identification, biology, and control.
   Identification of the two can begin as early as the egg stage. Fall Webworms can have up to four generations annually in our part of Texas, with each female moth laying only one egg mass in her life. These egg masses contain up to 600 hair-covered eggs up to two layers thick laid on the underside of leaves of the food host plant. 
   Such host plants will include a myriad of species but typically limited to sweetgum, oak, hickory, and pecan in our area. Upon hatching, the larvae will begin to build a silk web that will provide a safe environment from which they will feed. 
   Larvae of Fall Webworm will be green or yellow and covered with tufts of white and black hairs until becoming adult moths, when they will be up to 1½ inches long with dark spots on white wings.
Identification contrast to the Fall Webworm
   Walnut Caterpillars affect almost exactly the same host plant species. Like the Fall Webworm, the female of this species also will only lay one egg mass during her life that is also similar in size. The contrasts begin to appear at the egg phase of biology, with Walnut Caterpillar egg masses only one layer thick and void of hair or scales. 
   Larvae will hatch into reddish brown individuals feeding without the protection of a web, but moving as a colony as they feed. When larvae are young, leaves where they are feeding will be skeletonized. 
   Complete consumption of the leaf structure will occur as they approach the fifth instar (life stage). As Walnut Caterpillars progress through life stages, you may find cluster casts of the exoskeletons at random places throughout the affected host plant whereas Fall Webworm exoskeletons will be secluded to within the web.
   Damage by each of these species is limited to aesthetic, in most cases, in which host plant species will recover with a new budding of leaves. 
   Annual several infestations of the same host plant can result in more serious and lasting damage. 
   Control options for the homeowner or commodity grower will be the same for both species. 
   In young trees, egg masses and/or webs can be physically removed. Webs in older trees can be damaged by using a sprayer on a water hose to open the web and allow predator species to feed on larvae. 
   Before using any chemical option, read the label closely and follow it to the letter. Recommended insecticides for both species contain spinosad or Bacillus thuringiensis which are completely safe to humans and should be applied when larvae are young for best results. 
   Other insecticides that are effective include carbaryl and pyrethroid, but with each you will need to determine usage as a homeowner or producer due to potential impacts on beneficial or secondary insects and you, the applicator. 
The Crop Corner
   The lack of rainfall is becoming a more critical by the day for county farmers.
   All crops are currently in a critical stage of growth as the fruiting part of the crops are filling, which is the time of highest water usage affecting yield levels. Some farmers have the availability to irrigate while others do not. 
   Irrigation, however, can have a down side. Regardless of the source, water left standing on a crop too long can have adverse effects that could result in yield losses worse that those brought on by drought. 
   Matagorda County farmers are tasked with the decision to irrigate (if available) and how to get water applied in a manner that will benefit the crop without allowing water to stand. 
   No matter how the water is used, farmers incorporate best management practices keeping usage to a minimum and in a selected area. 
   As you walk the isles of the grocery store, send up a prayer for these men and women that are out in the heat busting their tail to put the food on those shelves. 
   Did you know?
The end result of cotton is 57 percent apparel, 36 percent home furnishings, and 7 percent industrial products.

Rate this article: 
No votes yet