After a year of limited insect pest movement, probably due to last year’s severe drought, landscape pest activity has been on the increase as of late.

The first report of Datana caterpillars feeding on live oak foliage was received early last week.

This is a pest that can quickly become a problem if conditions are favorable. These foliage feeders are often called oak leaf or live oak caterpillars in the Coastal Bend.

Usually two generations of Datana caterpillars appear in Kingsville each year.

However, there are years that the pest is active every month except for a short period of time in the winter.

The caterpillars are easily identified. They are hairy, black or grey in color, with white stripes running down the sides of their bodies. The hair is not dense but appears in tufts along the worm’s back.

Fully-grown caterpillars can be up to two inches long and about as thick as a pencil. In addition to defoliating trees these pest also leave droppings on concrete walks and drives.

One reason that populations develop rapidly is the fact that the adult Datana moth can lay 300 eggs in a mass.

Eggs are laid on the undersides of the leaves that the small worms will consume once they hatch.

Caterpillars hatch in about nine days and begin feeding. Young larvae feed only on soft tissue, leaving a skeletonized leaf behind, while older larvae feed on the entire leaf. It is during the final larval stage that the majority of feeding damage occurs.

Defoliation may be localized to one area on the infested tree, or in the case of severe infestation, total tree defoliation may occur.

The pest lives and feeds in groups and when disturbed they arch their heads and tails in a defensive posture.

Often the caterpillars can be found high in the tree on the outer branches. Many times the worms go unnoticed until they are spotted moving up and down the tree trunk.

When the pests have neared the end of the larval stage and finished feeding, they drop to the ground and pupate in the soil.

Weekly inspection of oak tree foliage to detect feeding colonies will insure that populations do not build to damaging levels.

Control of this leafeating pest can be achieved with common insecticides labeled for shade tree caterpillars. Good coverage is the key to successfully keeping the pest in check.