376 REport OF THE ENTOMOLOGISTS OF THE 
NATURAL CHECKS. 
Insects that live so much exposed while in the caterpillar stage 
as does the apple tree tent caterpillar fall an easy prey to many 
natural enemies which greatly lessen their numbers. The natural 
checks upon this insect may be classified under 5 heads, as follows: 
Climatic changes, birds, predaceous insects, parasitic insects and 
parasitic diseases. 
Climatic changes.— The caterpillars are most susceptible to 
these changes just after hatching or before they have become well 
established in the nest. A cold wind and rain storm at this time 
may kill great numbers of them. ; 
Birds.— Birds form one of the most important natural checks 
to many species of noxious insects. But unfortunately many of 
the birds which depend largely upon insects for food are being 
rapidly killed off, thus depriving the farmer of some of his most 
valuable allies in his conflict with his numerous insect enemies. 
The following birds are known to feed upon the apple trée tent 
caterpillar: The yellow-billed and the black-billed cuckoos, black- 
capped chicadee, Baltimore oriole, red-eyed vireo and wren. 
Nearly all of these have been observed in and about Geneva. 
Of these the yellow-billed and the black-billed cuckoos and black- 
capped chickadee are probably the most important. The former 
feeds readily upon the caterpillars, while the latter feeds upon the 
egos and young eaterpillars. According to Forbush, as quoted by 
Weed," the crow, chipping sparrow and yellow warbler also feed 
upon the caterpillars. It is probable that the warbling vireo may 
also be added to this list as Mr. W. P. Wheeler states that he re- 
cently saw one enter a nest of the caterpillars, remain for several 
minutes and give other evidence of feeding upon the young cater- 
pillars. Further observation will undoubtedly add many species 
to this list. The writer will be especially glad of any mforma- 
tion relating to the birds which prey upon noxious insects. 

11 N. H. Coll. Agrl. Expt. Sta. Bul. 38, p. 55. 
