ECONOMIC RELATIONS OF OUR BIRDS. 
515 
and groves, which must necessarily grow smaller and fewer as land increases in 
value. Again, their strong power of flight enables them to remain persistently 
upon the wing for hours at a time, and thus to do in the open fields, away from 
fences and trees, what other fly-catching birds are not able to accomplish. I 
have seen a squad of these birds follow a horse-rake back and forth across a 
stubble, apparently catching insects which were frightened into the air by the 
rake. They often hover about a flock of sheep, either to capture the flies which 
trouble them, or tlie insects which they startle while feeding. As the Swallow 
feeds to a considerable extent upon small dipterous insects and upon moths, we 
may expect to learn by careful study, that the Hessian fly and the clover-moth, 
which flies to some extent during cloudy weather, are destroyed by it in consid¬ 
erable numbers, as well as allied forms which affect similar situations. 
Food: Of eleven Barn Swallows examined, seven had eaten fourteen small 
moths; seven, forty diptera, among which were thirty-three tipulids ^Pac/iyr- 
rhia ferriigina 9J; two, six beetles; and one, a small dragon-fly. 
Insects (Cooper). Destroys numerous noxious winged insects (De Kay). Of 
two specimens examined by Prof. Forbes, each had eaten hymenoptera; one, 
leaf-chafers; one, diptera; one, hemiptera; and one, dragon-flies. 
62. Iridoprocne BICOLOR (ViEiLL.), CouES. WHITE-BELLIED SWALLOW. 
Group II. Class a. 
This Swallow is perhaps more abundant than the last species, and during the 
fall it often collects in very large flocks. By the middle of September, nearly 
all have left for the South. Early in the summer they are most abundant along 
the borders of streams and reedy lakes, especially where dead trees abound, in 
the hollow limbs and trunks of Nvliich they breed. In July and August they 
spread out over fields, pastures and meadows, oftenest in damp situations not 
far removed from water. During September they affect all open situations. In 
Eastern Massachusetts this species is said to have undergone a complete change 
in breeding habits. There it now breeds almost exclusively in martin-houses, 
and any sheltered and accessible box appears to answer their purpose. In Mas¬ 
sachusetts, too, they are most abundant in cities, while in sparsely settled dis¬ 
tricts they shun dwellings almost entirely. 
It is said that during the bi*eeding season this Swallow is somewhat quarrel¬ 
some, and even aggressive. Audubon knew of a pair driving the Barn Swallow 
from its nest and taking possession of it, but this act Dr. Brewer regards as 
exceptional. The change of habits which this species is undergoing in the East, 
suggests an apparently ready means of giving it a general distribution and con¬ 
siderable abundance with us, should this be desirable. I have no doubt that, if 
houses were put up along the fences about the fields, in a few years these birds 
would take possession of them and become much more abundant than ^hey are 
at present. Further study of their food appears to be necessary, however, be¬ 
fore such steps should be advised. The small species of dragon-flies to which 
these birds are apparently so destructive are very abundant in grain fields and 
meadows, especially those that are low and not far from standing or running 
water. It is known that these insects are predaceous, and a careful study of 
their food may show that they are very serviceable in holding in check such 
small insects as the wheat-midge and Hessian fiy. This swallow, however, it 
will be seen, stoops to capture plant-lice and dipterous insects just as small as 
the wheat-midge. Another very valuable trait in this species is its apparent 
destructiveness to weevils — insects so many of which are injurious. 
