2 BULLETIN 619, U. S. DEPARTMENT OF AGRICULTURE. 
In their relations to man the swallows, as a group, are as harmless 
as any family in the bird kingdom, and yet they are more closely re- 
lated to him socially than any other birds except domestic fowls. 
No complaint has ever been made that these birds harm either wild 
or cultivated fruit or seed or that they injure other birds. Although 
practically altogether insectivorous, they do not disturb domestic 
bees, and in a region where the silk-worm industry nourishes they 
would not harm the silkworms, for they do not eat Lepidoptera 
(caterpillars, moths, etc.) extensively, either larval or adult. The 
esteem in which swallows have always been held is well deserved. It 
is doubtful if there is a more useful family of birds in the world. 
Every provision should be made to induce them to stay about the 
farm or homestead- 
Swallows are pronounced flycatchers in the sense that they catch 
their prey upon the wing. Their mouths are specially adapted to 
act as scoops and take in insects in the air. Probably no other family 
of land birds spends so many of the daylight hours upon the wing 
as the swallows. It would follow, therefore, that their food would 
be taken mostly in mid-air and that it would be limited to insects 
that fly or jump. This would eliminate from their dietary such 
forms as caterpillars and beetle larvae and, in short, larvae in gen- 
eral; also such creatures as millepeds, sowbugs, snails, and, to some 
extent, spiders, although these are able to fly under certain conditions 
by means of their webs. 
That insects which spend most of their time in flight constitute 
the principal items of 'the swallow's food is verified by the examina- 
tion of 2,030 stomachs. This shows that Hymenoptera (bees, wasps, 
and ants) and Diptera (flies) constitute more than 50 per cent of 
the average food of the seven North American species here treated 
(see tabular summary, p. 28). Hemiptera (bugs, cicades, tree hop- 
pers, etc.) stand next in importance, although the species in general 
are not such good flyers and do not spend so much time on the wing 
as the Hymenoptera. The three insect orders, Hymenoptera, Hemip- 
tera, and Diptera, constitute nearly TO per cent of the average food 
of the swallows of the United States. Coleoptera (beetles) are less 
given to flying, and consequently are not so often taken, the small 
dung beetles (Aphodius) that fly over cow droppings in the evening 
being most commonly eaten. As all swallows apparently prefer to 
forage over the surface of still water, they take in their food such 
insects as aquatic Hemiptera and dragonflies, with other aquatic 
forms. 
The swallow's habit of taking its prey upon the wing and its re- 
luctance to alight upon the ground tend to exclude from its food all 
vegetable matter as well as nonflying insects. Stomach examination, 
while confirming this as a general rule, shows some exceptions. The 
