Scaffolds 99 index

ENTANGLEMENTS

(Art Agnello ama4@nysaes.cornell.edu, Entomology, Geneva)

The appearance of some unsightly webbing in a few trees here and there reminds us of the perennial activities of the fall webworm, Hyphantria cunea, a tiger moth (Arctiidae) whose larva feeds on almost all shade, fruit, and ornamental trees except conifers. This is a widespread defoliator that exhibits a preference for American elm, maples and hickory in this region, but a season with sparse OP sprays for apple maggot can bring the local populations into full view on apples and cherries. Adult females, white moths with a few dark spots and a 1-inch wingspan, deposit eggs in early spring, and the yellowish tan larvae pass through many instars (10-11) feeding within a large, compact web they produce that often encloses a whole limb of foliage.

FWW in Tree

FWW ON BRANCH

When disturbed, all the larvae in the web make jerky movements in perfect rhythm, possibly as a defense mechanism. According to Warren Johnson ("Insects that Feed on Trees and Shrubs"), nests of the fall webworm may be cut out of small trees and destroyed; alternatively, an application of a B.t. material can be effective. Although foliage is the most common food of the webworms, they have been known to do significant damage to apple fruits through surface feeding.

FALL WEBWORM LARVA

FWW DAMAGE

Normally, however, this insect is detrimental mainly to the beauty of the host and is thus more a nuisance than a true threat to the tree's health.

End of this issue: Scaffolds 1999 Index