GUEST COMMENTARY

JACQUE KYLE -- FANNIN COUNTY MASTER GARDENER

BONHAM -- Summer has arrived, and with it come a variety of pests that are detrimental to the trees, shrubs and plants. Below, Jacque Kyle, Fannin County Master Gardener, answers questions about several common pests of north Texas and southern Oklahoma.

What are those webs in the trees?

They are webworms. This is a common caterpillar pest of trees. There are several varieties of webworms: fall webworm, eastern tent caterpillar and forest tent caterpillar. The ones in our area are the fall webworm and attack over 88 kinds of plants, including fruit, nut and ornamental trees and shrubs. Heavy infestations are rarely fatal, but if they occur repeatedly over several years, they can stress trees and make them more susceptible to drought, disease or other insect pests.

The fall webworm moth is white and has a wingspan of one to one and one-half inches. Full-grown larvae are about one inch long, pale green or yellow and covered with tufts of long white and black hairs. Two to three generations of fall webworms occur in northern areas of Texas, starting as early as April and continuing. The last generation, occurring in the fall and giving the insect its name, is usually the most damaging.

Fall webworms can often be controlled without insecticides by removing and destroying any leaves that contain egg masses. Larvae (worms) may be knocked out of low-hanging branches into boxes or bags for disposal. The branches with the webs may also be cut off and put into boxes or bags for disposal.

There are many beneficial insects that attack the egg and larvae of the fall webworm, and you can help these predators by tearing open the webs. Hose-end sprayers or commercial high-pressure sprayers are best for reaching upper portions of tall trees to tear open webs. The webs protect the larvae from rain, predators and insecticides.

How can I get rid of the bagworms?

Although bagworms are not abundant every year, once a plant is infested it can become a persistent problem unless controlled.

Texas has several species of bagworms. The species found on most evergreens in east-central Texas has one generation per year. Eggs are laid in the fall and hatch in the spring. They grow through the summer and pupate in August or September. In three weeks, the adult moth emerges, mates, deposits eggs and dies.

Birds, insect parasites and insect predators are natural enemies of bagworms and can help keep outbreaks brief. Handpicking bagworms off the plants is the cheapest way to control them, particularly in winter months. Destroy all bags you pick off because eggs in bags thrown on the ground will hatch in the spring and can reinfest the plant. If this is not practical, apply insecticide spray soon after bagworm eggs have hatched or while the larvae are small and feeding. Chemical control is not effective when the caterpillars close their bags to molt or pupate or after the moth has left. (from Extension publication E-480)

How can I control these grasshoppers?

Grasshoppers are among the most widespread and damaging pests in Texas. There are about 150 species in the state, but 90 percent of the damage is caused by only five of them. They cause some damage every year, but outbreaks can be destructive.

The main factor affecting grasshopper populations is weather. Hot, dry summers and warm autumns allow grasshoppers more time to feed and lay eggs. It also increases the survival of nymphs and adults. Usually only one generation of grasshoppers is produced each year.

Grasshoppers have many natural enemies that help control the populations. Fungi, protozoans and nematodes, as well as birds and mammals, feed on grasshoppers in various stages. However, these have little effect on large populations. There are several mechanical and cultural methods to help control populations (see Extension publication E-209). Some gardeners use the catch, cut off the head with scissors and release method.

When more control is necessary, select a suitable insecticide based on where the grasshoppers are feeding: trees, shrubs, flower gardens, vegetable gardens, etc. Insecticides are labeled for specific insects in specific sites. Be sure to read the label and follow instructions for the site you will be using it in. (from Extension publication E-209)

For more information, call the Fannin County Texas AgriLife Extension Office at 903-583-7453.