Webworm tents soon to appear

Webworm tents soon to appear

Webworm tents soon to appear

Published: Wednesday, June 25, 2014 at 02:26 PM.

The fall webworm, Hyphantria cunea, is a moth known principally for its caterpillar, which builds impressive silk tents that sometimes enclose entire branches of hardwood trees.

The tents appear in late summer or fall. Defoliation by fall webworm caterpillars does not usually cause damage to the tree, since they feed in late summer or fall, just before leaf drop. While the nests are unsightly, the caterpillars are not believed to harm otherwise healthy trees.

Fall webworm caterpillars will feed on any one of over 100 tree and shrub species. Preferred host plants include hickory, pecan, walnut, elm, alder, willow, mulberry, oak, sweetgum, and poplar.

The moth is native to North America, ranging from Canada to Mexico , and is one of the few insect pests introduced from North America into other continents. Introduced into the former Yugoslavia in the 1940s (firstly recorded in 1949), it is now found in Europe from France to the Caspian Sea and in Central Asia where it continues to expand its range. It was also introduced into Japan in 1945 and is now present across the northern hemisphere.

One generation per year emerges in the northern part of this moth’s range. In the southern part of its range, there are two or more generations annually.

The caterpillars are highly variable in color, ranging from a pale yellow, to dark grey, with yellow spots and long or short bristles. There are two cream stripes along the sides.

After the caterpillar enters a cocoon, the pupa stage overwinters in the bark and leaf litter at the base of the trees. It is dark brown and about 10 mm long. The thin brown cocoon is made of silk covered with bits of twigs and dry leaves.

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