FARMERS’ 
BULLETIN 
WasuinctTon, D. C. 662 May 1), 1915 
Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
THE APPLE-TREE TENT CATERPILLAR.’ 
By A. L. QUAINTANCE, 
In Charge of Deciduous Fruit Insect Investigations. 
INTRODUCTION. 
The conspicuous, unsightly nests or tents of the apple-tree tent 
caterpillar (fig. 1) are familiar objects in the spring in trees along 
roadways, streams, and fences, in neglected orchards, and elsewhere. 
The gregarious caterpillars construct the tents for their protec- 
tion, and these, at first small, are gradually enlarged as the larvee 
grow, often to a foot or more in height and diameter, the size varying 
with the number of individuals in the colony. The caterpillars 
feed upon the foliage of the trees, stripping the leaves from the limbs 
adjacent to the nest, and if there be several colonies in a tree, as is 
frequently the case during periods of abundance, the foliage may 
be quite destroyed, leaving the branches as bare as in midwinter 
(fig. 2). 
DISTRIBUTION AND FOOD PLANTS. 
The tent caterpillar is a native American species occurring quite 
generally in the United States from Canada south to Florida and 
westward about to the Rocky Mountains. From the Rockies to the 
Sierras, according to Dyar, the species is replaced by another of the 
same genus,? which ranges from Canada to Mexico, and this latter 
form in the Pacific Northwest is replaced by still another species. 
The tent caterpillar has been a troublesome pest from the earliest 
times. As stated by Fitch, its injuries in Massachusetts in the 
years 1646 and 1649 led the early settlers to term these ‘caterpillar 
years.”” At rather long and irregular intervals the caterpillars have 
been excessively abundant in different parts of their range, but more 
1 Malacosoma americana Fab. 2 Malacosoma fragilis Stretch. 3 Malacosoma pluvialis Dyar. 
84973°—Bull. 662—15——1 
