110 USEFUL BIRDS. 
to tree culture cecropia has no equal in some portions of the 
prairie country, and that its large caterpillars often defoliate 
entire groves. Mr. W. C. Colt, who has had experience in 
raising trees in Dakota, told me that the caterpillars of this 
Fig. 3'7.— The larva of the cecropia moth, a destructive leaf-eating insect, 
held in check by birds. 
and other large species were terribly destructive there. As 
groves and orchards became established, however, and arbo- 
real birds spread over the country, these caterpillars were 
reduced to a state of comparative harmlessness. There is 
good reason, therefore, for the belief that the caterpillars so 
commonly eaten by practically all arboreal birds would, to- 
gether with the borers, destroy all the forests were the birds 
to be banished from their chosen haunts.? 
1 The latter part of this chapter consists of revised portions of several papers 
by the author, originally published by the Massachusetts State Board of Agri- 
culture. 
