Saturday, September 25, 2010

Fall Webworms Are Likely to be Found Soon

The fall webworm, Hyphantria cunea (Drury), is usually noticed when the light gray silk webs are discovered on trees in late summer and early fall. They are considered pests of shade and ornamental trees in urban areas, by attacking more than 88 plants as they enclose leaves and small branches with their webs. Four generations occur in the south Texas, with 2 to 3 generations occurring in north Texas. The last generation in the fall is usually the most damaging.
The caterpillars build webs soon after hatching and they will remain inside the web consuming the tender parts of the leaves. If the caterpillars eat all of the leaves within the web, then new foliage will be enclosed within the webbing. These caterpillars are 1 inch in length, pale yellow or green in color, and covered with white and black tufts of long hair. The caterpillars will molt 6 or 7 times before dropping to the ground to pupate. The pupae overwinter and the adult moths emerge the following spring.

Some Control Options:

Some Non-Chemical Control Options:
1)Small webs can be removed by pruning and destroying the infested portions of branches.
2) A stick or pole can be used to snag individual webs to allow natural enemies such as yellow jackets, paper wasps and birds to eat the webworms.
3)Bacillus thuringiensis, B.t,. is effective against fall webworms if it is applied when the caterpillars are small. It is better to apply after the eggs hatch and the web is not dense.

Some Chemical Control Options:
Chemicals should be applied after eggs hatch, since they are most effective on young caterpillars. Insecticides such as those containing spinosad and tebufenozide as active ingredients can be used. Multiple applications may be needed as generations continue.

Fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), web on pecan. Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

Monday, September 20, 2010

Remember to Treat for Fire Ants This Fall

Remember that the end of summer means treating for fire ants! Since the weather has been so hot this summer, we might not necessarily see the fire ant mounds in our yards. However, they are still in the area and are living deep in the soil. Since fire ants are a medically important insect pest, we need to treat this fall to decrease their populations next spring.
Before treating for fire ants, one must first survey the area to determine the number of mounds. If less than 5 mounds are present in a quarter acre plot, then it is advised to treat the individual mounds with a bait, drench or dust.
If more than 5 mounds are present, then treatment should be broadcasted over the entire area. A fire ant bait or contact insecticide may be used. Fire ant baits are comprised of defatted corn grit covered with an insecticide and soybean oil. Before broadcasting the fire ant bait, foraging activity should be evaluated by placing a potato chip or hot dog next to a mound. If fire ants find the food within fifteen minutes, then it is an appropriate time to broadcast the fire ant bait. Fire ants will typically forage when the soil surface temperature is between 70 and 90° F. Fire ant baits should never be watered into the soil and they should not be used if they smell rancid. Contact insecticides can also be broadcasted over the entire area and these need to be watered into the soil. One contact insecticide, containing the active ingredient fipronil, can be used for fire ant control and will usually provide 9 to 12 months control.
Both fire ant baits and contact insecticides can be broadcast using a hand-held spreader for small areas or a Herd Seeder can be mounted onto a truck or ATV to treat larger areas.
For more information, please visit the fire ant webpage at

Fire ant mound in a landscape. Photo by Dr. Bart Drees, Professor and Extension Entomologist, Texas A&M University.