PEST PROFILES: MOTH AND BUTTERFLY CATERPILLARS
Click on image to view larger. Webworms
Spring webworm and fall webworm larvae form a web that can cover individual leaves, leaf clusters or whole branches, growing to several feet in diameter. Larvae grow to about 1 inch long, with pale yellow or greenish bodies marked with a broad mottled stripe containing 2 rows of black tubercles down the back. They are covered with tufts of long whitish hairs. Adults are mostly white with dark spots on the wings.
Larvae produce loose webbing around leaves and branches; larval hairs may cause skin irritation. Larvae will feed on leaves of a large number of tree species. Webworms can appear as early as April in south Texas. However, the last generation is the most damaging.
Overwinters as pupae in a silken cocoon in leaf litter or in cracks on rough bark. Adults emerge in spring. Oviposit eggs in masses on leaf undersides that appear covered with hair. First instars begin feeding on leaves, spinning silken webs enveloping their feeding sites. There can be up to eleven instars. Two to 4 generations occur per year, depending on locality.