REPORT OF THE STATE ENTOMOLOGIST 1902 97 
habits to a greater degree than when they are very abundant, 
since in this case the supply of food is soon exhausted and 
they are forced to migrate. When these caterpillars molt, they 
gather in masses on the branches and cover themselves with a 
scanty mass of silk. When preparing to change to the pupal 
stage, several of the caterpillars spin up in a common cocoon 
within the leaves at the tip of the branches. When numerous, 
they frequently pupate in masses under fences and clapboards, 
or on the trunks and larger branches of the trees. 
The webs of the brown tail moth should not be confounded 
with those of the tent caterpillar or the fall webworm. They 
may be distinguished from those of the tent caterpillar by being 
placed at the tips of the branches, while the tent caterpillar con 
structs its tent in a fork of the limbs. The latter insect rarely, 
if ever, attacks pear, which is a favorite food plant of the brown 
tail moth. The fall webworm, while often found on peartrees, 
spins a large open web at the ends of the branches and feeds 
within this web. This insect does not appear until after the 
brown tail moth has ceased to do damage. 
Food plants. This species has been recorded on a considerable 
number of food plants, but, according to Professor Fernald, pear 
seems to be the favorite of this insect in the infested region, 
though winter webs have been found in addition on apple, quince, 
plum, cherry, peach, oak, maple, elm, rose and grape. 
Irritation caused by the hairs. This has been referred to above; 
and, as there stated, is frequently very severe and annoying. 
Investigations by Mr F. J. Smith show that the trouble is a 
mechanical one, and is not, as at first was supposed, due to any 
poisonous irritant substance in the hairs. The nettling of the 
skin may be caused by contact with the caterpillars, both old 
or young, or the cocoons, though in the latter case contact is not 
necessary since hairs from them are blown about by the winds. 
Professor Fernald cites the statement of an English journal to 
the effect that travelers are often affected, when the wind blows 
strongly from infested hedges along the road. 
Natural enemies. A number of parasites have been bred from 
the pupae in this country. Professor Fernald records the rearing 
of Phaeogenes hebe Cress, Diglochis omnivora 
Walk., Euphorocera claripennis Macq. and a large 
number of unnamed dipterous parasites. He states that the 
work of Diglochis is specially valuable and worthy of commen- 
