INSECT ENEMIES OF WESTERN FORESTS TeAt 
The caterpillars of this tussock moth are striking looking creatures, 
decorated with brightly colored tufts of hairs. When full grown 
they are from three-fourths to 1 inch in length, with gray or light- 
brown bodies and black, shiny heads. There are two long brushes 
or pencils of black hairs fully one-fourth inch in length, suggesting 
horns, directly behind the head, and a similar but longer tuft at the 
posterior end of the body. On the upper side of the first four and 
the last abdominal segments are dense, light-brown or cream-colored 
tufts of hairs about one-sixteenth of an inch in length, and numerous 
red spots. Along the sides of the body are somewhat broken, nar- 
row, orange stripes, while the lower side of the body is nearly naked, 
with the prolegs only sparsely covered with hairs. 
The adult moths are far more ordinary looking than their hand- 
some larvae, being a dull brownish gray. The males are about 
one-half inch long and have a wing expanse of nearly an inch. The 
wingless females are about one-half the length of the males. 
Normally there appears to be one generation a year. The small 
caterpillars hatch from the eggs and commence feeding on the new 
foliage early in spring, but it is not until about the Ist of August 
that the defoliation is likely to become severe enough to be noticeable 
at a distance. The larvae reach full growth early in August and then 
pupate. The moths appear the latter part of August and mate soon 
after emergence. The winter is passed in the egg stage. 
One of the most important parasites is a tachinid fly, somewhat 
larger and more hairy than the ordinary housefly. The larvae of this 
fly live in the caterpillars and emerge after these have formed their 
cocoons. A very small wasplike insect, 77ichogramma minutum 
Riley, attacks the eggs and destroys a high percentage of them. 
There are at least five other wasplike insects that are important 
parasites of the larvae. 
Determination of the feasibility of artificial control of this Ge- 
foliator involves not only the consideration of effective methods but 
the cost of applying them. The spreading of arsenical dust by air- 
plane probably would offer the best chance of success of any method, 
but at this time it cannot be recommended on account of risk and 
cost. Such methods as collecting and destroying the egg masses 
during the winter months, jarring the caterpillars from the trees, 
banding the trees to prevent ascent of the caterpillars, and power 
spraying, are applicable to the control of this insect only under park 
or shade-tree conditions. | 
Other closely related species of tussock moths which feed on forest 
trees in the Western States include: 
Species Host and distribution 
Hemerocampa oslari Barnes__—-~- White fir. California and Colorado. 
Hemerocampa vetusta Bdv_--_--~ Oak, poplar, willow, and various other 
broadleaved trees. Pacific coast. 
Hemerocampa gulosa Hy. Hdw__— Oak. California Sierras. 
Hemerocampa leucostigma A.andS. Poplar and other broadleaved trees. In 
the East, and west into Colorado and 
British Columbia. 
Nototophus antigua, Lies —--—---~ Alder, ash, aspen, larch, oak, pine, poplar, 
willow, and other broadleaved trees and 
shrubs. From California to British Co- 
lumbia and east to Montana. 
