Fall webworm (caterpillar)

Description:

A large outbreak of these pest this year. A fuzzy caterpillar with a black head with some white markings (pic2). They create large webbed masses in deciduous trees that will kill that part of the tree that it encases and sometimes the entire tree will die. Pics 3-6 show the web in a young alder tree.

Habitat:

Spotted at the Nisqually National Wildlife Refuge.

Notes:

The moth is native to North America, ranging from Canada to Mexico. It is one of the few insect pests introduced from North America 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.(Wikipedia)