More than 20,000 acres of fir trees in the Southern Sierra were defoliated in the late 1990s by the Douglas fir tussock moth (Orgyia pseudotsuga). The larvae of this moth feed on many types of fir trees, including the white fir (Abies concolor). But thatís not the biggest problem for outdoor enthusiasts; in its caterpillar stage, the tussockís hairs cause itching and rashes for many people. Outbreaks of tussocks can last up to three years, dying off in a viral outbreak that is harmless to people.
Read and add comments about this page