ECONOMIC RELATIONS OF OUR BIRDS.                     479
Tabular Summary of Economic Relations showing the number of specimens con-
taining animal and vegetable food, and the number of insects and spiders
taken front the stomachs, classified as to economic relations under the heads
Beneficial, Detrimental and Unknown Relations.
NUMBER AND NAME OF SPECI-   CLASSIFICATION  RATIOS RE-PRESENTED BY LINES.
MENS EXAMINED.           OF FOOD.
26        Animal food .
1  7     Vegetal food .....
Of twenty-seven Bluebirds 20             g 442DDetrimentl.
3 e    5 Beneficial ...
11    22 Unknown ..........
Table showing the kinds and number of insects and spiders eaten by the
Bluebird.
NUMBER AND NAME OF SPECI-  CLASSIFICATION   RATIOS REPRESENTED BY LINE.
MENS EXAMINED.           oF FOOD.
1      2 Ants    . .
6     10 Lepidoptera .
8     13 Beetles .
It 1           Heteroptera .
Of twenty-SevenBluebirds 17 ;d 22 Orthoptera .......
examined   .         .     22.....hoptera.
2      2  Spiders ...........
24    40 Adult forms.
6      9 Larv ............
2     10 Grasshopper eggs.
10. SIALIA SIALIS (LINN.), HALD. EASTERN BLUEBIRD. GROUP I. CLASS b.
The Bluebird has so many excellent qualities that it promises to become,
under proper management, one of the most readily utilizable insect-destroyers
which we have among birds. It is, with us, almost exclusively inseotivorous,
and is especially destructive to grasshoppers. It captures its prey upon
the wing
and upon the ground, giving it a wide range of food, from which it may be
ex-
pected to maintain, under favorable conditions, a steady and considerable
abun-
dance. Its long summer residence, its rearing of two, sometimes three. broods
each season, its fondness for cultivated fields, and its willingness to breed
in
bird-houses protected from the ordinary enemies of birds, and beyond the
dis-
turbance of the machinery and live-stock of the farm, are other qualifications
which tend to place it in the front rank of usefulness.
How to cause this bird to take and maintain a greater abundance than it now
has is a question of great practical importance to all classes of farming.
The
fact that its familiar and confiding nature has not made it more numerous
among
us, appears to be readily explained by its breeding habits. In its unmodified
condition, its nest is usually placed in some hollow limb or tree; and as
a natural