USEFUL INSECTS EATEN BY THE ROSEBREAST. 43 
As just noted, almost 6.5 percent of the total food is Hymenoptera, 
and as this group contains some of the most useful of all insects, it 
must be ascertained how many, if any, of these forms fall a prey to 
the bird. The beneficial Hymenoptera are the small parasitic species, 
the eggs of which are deposited in the bodies of caterpillars and in 
the eggs of many insects, to develop there and later destroy their 
hosts, and the larger wasps, which store up caterpillars and other 
creatures as food for their young. Very few parasitic species were 
found in the stomachs, the larger Hymenoptera apparently being 
preferred. In many cases a single wasp composed from 40 to 90 
percent of the stomach contents of individual grosbeaks. It is pos- 
sible that among these are some of the highly beneficial solitary 
wasps, but the probabilities are that most of them belong to the more 
abundant, gregarious species, which although often beneficial would 
lose little by the destruction of few of their number. 
Fifty-four of the 176 grosbeaks examined were found to have 
caten Hymenoptera of some sort, which shows that the bird has a 
decided liking for these insects; but, as just mentioned. few bene- 
ficial species are eaten, while a number of injurious ones are devoured. 
One grosbeak secured a cuckoo fly (Chrysis sp.), which is a parasite 
of the useful solitary wasps. Three fed upon sawfly larvee, which 
have habits like caterpillars, and are injurious to roses, currants, 
pear, willow, and other plants. One bird when collected had 10 
sawfly larve in its beak, which it was probably gathering for its 
young; whjle in the stomach of another grosbeak were 24 of these 
larvee, which constituted 60 percent of the contents. The few ants 
taken are injurious, especially those of the genus Camponotus, which 
sometimes devour the wood of living trees, hollowing them out to 
mere shells. Two rosebreasts ate little mining bees (Andrena), one 
consuming 26 of these and nothing else. They have no special 
economic significance except as carriers of pollen. 
Passing now to beetles, this grosbeak was found to prey upon 
members of three useful families, the ground-beetles (Carabide), 
ladybirds (Coccinellide), and fireflies (Lampyride). Seven birds 
ate predaceous ground-beetles, but since they compose only a little 
more than 0.5 percent of the food from May to September, little 
harm is done. One of the 7 grosbeaks captured a large shining black 
ground-beetle (Pasimachus depressus), which is about an inch in 
length and is one of the most powerful insects of the family. 
Three birds ate coccinellid beetles, one securing a twice-stabbed 
ladybird (Chilocorus bivulnerus), a noted enemy of scale insects. 
If many such beetles were eaten, damage would be done, but as they 
compose less than 0.2 percent of the total food, it is evident that only 
occasionally one is snappeckup. Moreover, the grosbeak compensates 
