Arthropods • Earth.com

Fall webworm moth

(Hyphantria cunea)

galery

Description

The fall webworm (Hyphantria cunea) is a moth in the family Erebidae known principally for its larval stage, which creates the characteristic webbed nests on the tree limbs of a wide variety of hardwoods in the late summer and fall. It is considered a pest but although unsightly, does not harm otherwise healthy trees. It is well known to commercial tree services and arboriculturists. The adult fall webworm has a wingspan of approximately 30 mm and is generally white-colored, although some individuals may have dark-colored marks. The moth is native to North America, ranging from Canada to Mexico and has been introduced into other continents. Introduced to what was formerly Yugoslavia in the 1940s (firstly recorded in 1949), it now has occupied probably its entire range in Europe from France to the Caspian Sea in the east as well as penetrated into Central Asia: Turkmenistan (from 1990 to 1993), Uzbekistan (Fergana valley from 1996 to 1997), Kyrgyzstan, and southeastern Kazakhstan. It was also introduced into Japan in 1945 and has adjusted its number of generations per year since its arrival. It spread into China, southern Mongolia, Korea and southern Primorsky Krai of Russia so that now it is considered holarctic in distribution. The fall webworm originated in North America but spread very quickly across the world due to factors such as trade and rapid transit. One generation per year emerges in the northern part of North America, with larvae appearing in late summer through early fall. South of an approximate latitude of 40°N there are two or more generations annually, with webs appearing progressively earlier further south. The adult moth lays her eggs on the underside of leaves in 'hair'-covered clusters of a few hundred. Eggs hatch in about a week. The caterpillars are highly variable in coloration, ranging from a pale yellow to dark grey, with yellow spots and long and short bristles. There are two cream stripes along the sides. The two races one more common in the north, the other in the south differ in head capsule coloration. The maximum length of larvae is 35 mm. Webs are progressively enlarged and much messier looking than those of tent caterpillars (which occur only in spring and have shorter hairs and very little yellow on their bodies); also, webs from the fall webworm are concentrated to the tips of the branches, whereas the tent caterpillar webs are largely found in the unions. Larvae feed inside the tents until the late instars.

Taxonomic tree:

Domain:
Kingdom: Animalia
Phylum:
Class: Insecta
Order:Lepidoptera
Family:Arctiidae
Genus:Hyphantria
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