Tree caterpillars abound

April 12, 2011 at midnight
Updated April 11, 2011 at 11:12 p.m.

By Joe Janak

Numerous types of caterpillars can be a problem to homeowners' trees, and once again, they have built up numbers recently in areas around Victoria.

Caterpillars are seen in live oak, pecan and other trees and feed on leaves in early spring. They feed for about three weeks, going through several stages, molting or shedding their skin about five times before becoming a full-grown worm about 1 -inch long.

Walnut caterpillars generally feed on pecan trees and are reddish/bronze color in the early stages, and then change to a gray/black color in the final larvae stage.

Forest tent caterpillars do not make a web-like tent, but have tiny white key-hole spots on the top of their back.

Eastern tent caterpillars do make a tent and have a single, white line down their back. Both are seen feeding on live oaks primarily.

Another caterpillar that feeds on oaks is the tussock moth caterpillar, which has long, hair-like antenna and white, fuzzy tufts on its back. And then there are the fall webworms, which are fuzzy pale yellowish-green and feed on many trees.

The final stage of any of these caterpillars may molt on the lower trunk of the tree. This is an ideal time to stop the cycle, if you can catch them molting as they are grouped together, verses spread out over the tree. Spraying the colony of worms with an insecticide or soapy water will kill that colony. Just a little soapy water mixed at about 1 cup per gallon water will cause the worms to suffocate. Save the rest of the soapy water for future colonies.

Other than that, there is no drench you can put on the ground to kill the worms. Although spraying the foliage with organic products, such as Bt or spinosad, or any of the other approved insecticides, such as malathion or sevin will kill them. Not stopping the last instar, may cause near total tree defoliation as 80 percent of what they consume in their life is done so in the last five days. Usually, the trees will leaf out with minimal problems. Although repeated leaf loss can weaken a tree.


This is the honey bee swarming season. You may see a swarm of bees around your house. They are best left alone, as we need to save as many bees as we can. They usually leave in two to three days when they find a suitable nesting site. Beekeepers will usually come pick them up if they are outside a structure and easy to retrieve. For a list of beekeepers, contact the Extension office at 361-575-4581.


Farmers need not go far and see the effects of the current dry spell. Corn is already wilting, and in some fields, it is not coming out of the wilt stage even on cloudy days. The lack of rain, warmer than normal temperatures and extremely high winds are taking a toll on the area crops and pastures.

With a recent forecast from the National Oceanic and Atmospheric Association showing the next three months to be warmer and drier than normal, farmers, ranchers and even homeowners need to start taking action. That means anything from starting to conserve water to mulching with organic matter around flower beds and in gardens to conserve soil moisture. Drip irrigation is the most efficient method of applying supplemental water especially in these high winds.

Homeowners, as well as farmers and ranchers, need to be on the lookout for pests which, can further make growing a crop in a drought difficult. Weed control is of utmost importance. We've seen fields lately where even when the weeds were killed, it was too late as subsequently planted crop seed was slow to germinate or didn't, because of reduced soil moisture caused by the weeds. Some recent pests, besides weeds, growers need to be on the lookout for include chinch bugs, aphids, caterpillars, grasshoppers and others. Checking a crop frequently and catching an infestation early may be the saving grace if the dry weather continues.

From noon to 1 p.m. on April 25, Lunch and Learn with the Masters will be held at the Pattie Dodson Health Center, 2805 N. Navarro St. The topic is "Beautiful Flowering Landscape Plants," by Barbara Hennig, Victoria County Master Gardener. The event is free to the pubic.

Joe Janak is a Victoria County extension agent.



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