Web worms are called as such because of their characteristic in creating webbed nests on tree limbs of hardwoods and gardens in fall and late summer.

Web worms

Web worms are called as such because of their characteristic in creating webbed nests on tree limbs of hardwoods and gardens in fall and late summer.

Bristling with silky hair, these caterpillars, which are yellow, are actually moth larvae that weave expansive webs binding together the ends of branches.

The larvae, consists of two races, one common in the north and the other in the south, appears in late summer through early fall.

The adult lays eggs on the underside of leaves in hundred clusters covered in “hair” like substance. In about a week, the eggs begin to hatch.

During the early larval stage that lasts from 4 to 6 weeks, the young larvae feed on the upper surfaces of the leave only. As they mature, the web worm feeds on the entire leaf; and continues to do so building larger webs until late autumn.

At which stage, they enter the pupa stage. The pupa is dark brown and about 10 mm long. It hibernates inside its cocoon in loose bark and leaf litter at the tree base during winter.

The webs resemble dirty rags and are filled with black droppings and wriggling worms. Interestingly, such webs protect the caterpillars inside from most pesticides.

Their hideous sights destroy the aesthetic appearances of any garden. Their favorite spots include deciduous trees, vines and shrubs.

The damage, though, reaches beyond aesthetics. Web worms feed on the nuts of pecan, walnut, American elm, hickory, and fruit trees, binding them to their webs.

Certain maple trees, persimmon and sweetgum are either readily eaten or preferred as hosts. The same plight happens to cottonwood, willow, and alder. In addition, they render the branches, and sometimes, even the whole trees defoliated.

In the Northern USA, the worms appear late in the season when deciduous leaves naturally shed. Nevertheless, the unsightly blemish that nest blemishes the landscape remains for many months.

Not only mature trees become a host. Even sapling trees can be devoured, and dwarf trees be stripped of their foliage overnight.

Known in its scientific name hyphantria cunea, it belongs to Arctiidae family of tiger moths. These yellow caterpillars come in over 600 species, and have Canada and Mexico as their native lands. In 1940, it was introduced to what was formerly known as Yugoslavia.

Its impact is felt as far as the entire range in Europe, to the east in Japan, Korea and China. Its distribution today is considered Holarctic.

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Top Of Web Worms Page Photo credit to Flicker.