284 ENTOMOLOGY 
than one tenth that of the sunfishes, and the principal food re- 
sources of half-grown sheepshead; but were rarely taken by 
the sucker family, and made only five per cent. of the food of 
the catfish group. 
“The various larve of the dragon flies, on the other hand, 
were much less frequently encountered. They seemed to be 
most abundant in the food of the grass pickerel (twenty-five 
per cent.), and next to that, in the croppie, the pirate perch, 
and the common perch (ten to thirteen per cent.). 
“Case-worms (Phryganeidze) were somewhat rarely 
found, rising to fifteen per cent. in the rock bass and twelve 
per cent. in the minnows of the Hybopsis group, but otherwise 
averaging from one to six per cent. in less than half of the 
species.” 
Insects in Relation to Birds.—From an economic point 
of view the relations between birds and insects are extremely 
important, and from a purely scientific standpoint they are no 
less important, involving as they do biological interactions of 
remarkable complexity. 
The prevalent popular opinion that birds in general are of 
inestimable value as destroyers of noxious insects is a correct 
one, as Dr. Forbes proved, from his precise and extensive 
studies upon the food of Hlinois birds, involving a laborious 
and difficult examination of the stomach contents of many 
hundred specimens. <All that follows is taken from Forbes, 
when no other author’s name is mentioned, and though the 
percentages given by Forbes apply to particular years and 
would undoubtedly vary more or less from year to year, they 
are here for convenience regarded as representative of any 
year and are spoken of in the present tense. About two thirds 
of the food of birds consists of insects. 
Robin.—The food of the robin in [linois, from February to 
May inclusive, consists almost entirely of insects; at first, 
larve of Bibio albipennis for the most part, and then caterpil- 
lars and various beetles. When the small fruits appear, these 
are largely eaten instead of insects; thus in June, cherries and 
