Home & Garden Tips
The Pine Webworm
By Roosevelt McWilliams County Extension Agent

The pine webworm occurs in southern Canada and throughout most of the eastern half of

the United States. It attacks pitch, Virginia, white, shortl eaf, longleaf, loblolly, and slash pines.

The pine

webworm usually attacks one and two year seedlings, but will infest sap- lings and large trees. Rarely is defoliation severe enough to kill the seedlings, but it may have some growth impact.

The adults are about 12 mm long. They emerge from the ground after the larvae drop to the ground from their nests and pupate. The larvae of pine webworms range from 18-20 mm and are tannish, to yellowbrown in color with two darker longitudinal strips along the back. When these larvae hatch, they spin silk threads among needles and begin to mine the needles within the web. The larvae tie foliage together with their silk to provide them with an abundance of food and to protect them from enemies.

These webs are commonly 5 cm web nests usually made on terminal twigs and contain dead needles and insect excrement. In most cases, the injury to the tree has been done and the nest vacated before the pest is noticed.

The most noticeable sign of attack, and usually the first, is a large mass of frass and excrement pellets entangled in a network of silken webbing. Close examination of this mass of material will usually reveal one or more larvae.

The eggs usually lay on seedlings, or occasionally, on larger trees between May and September. After the eggs hatch, the caterpillars live in silken webs surrounded by masses of frass and feed on the needles. After feeding is completed, the caterpillars drop to the ground and pupate in the soil. In the South, there are usually two generations per year.

In plantations, hand-picking is an effective method of control. When high value nursery stock becomes infested, chemical control may become necessary.