122 GIANT SILK-WORMS. 
jured by the variations of temperature during the winter. 
Late in May or early in June the pupal case is ruptured by 
the struggles of its occupant, and the newly born moth 
begins to work its way out of the cocoon; to lessen the 
labor a fluid is secreted about the mouth, which softens the 
fibres; then a tearing, scraping sound is heard, made by the 
insect working with the claws on its fore-feet, pulling away 
the softened threads and packing them on each side to make 
a passage for its body. 
The natural enemies of this species are usually sufficient 
to present an undue increase of these voracious caterpillars, 
but if for some reasons such enemies are absent the cater- 
pillars become very numerous and destructive. This is 
especially true in the windbreaks in our open prairies, where 
they cause sometimes considerable troubie. Orchards and 
nurseries also suffer from time to time, but as a general rule 
these insects are not numerous enough to inflict serious in- 
jury. Their large size, and their work in defoliating trees 
and shrubs, soon attract attention, and they can readily be 
removed by hand-picking. The caterpillars are destroyed 
by numerous parasitic insects, chief among which are 
Tachina flies, (Fig. 124, Plate XIV.) the Long tailed Ophion 
(Ophion macrurum),the Cecropia Chalcis-fly (Smicra mariz), 
Cecropia Cryptus (Cryptus extrematis) and others. Birds 
are also effective in destroying both caterpillars and pupe; 
the Hairy Wood-pecker eats the pupz of a large number of 
cocoons during the winter. Many others are destroyed by 
the Blue-Jay, and by our odoriferous friends the Skunks, who 
find most of the cocoons formed near the ground. 
The caterpillars of this moth are very general feeders, 
and in 1882 in Papilio a list of 49 species of plants belong- 
ing to 20 genera was given as their food plants. Since that 
time many other plants have been found that are to the 
taste of these voracious feeders, and among them apples, 
plums, cherries, all kinds of small fruit with the exception of 
the grape-vine; other cultivated plants also furnish food. 
