CONSTITUENTS OF FOOD. 
9 
Fig. 3.— Leaf-beetle (Systena 
blanda) (after Chittenden; 
loaned by Division of Ento- 
mology). 
and Acrididse — see fig. 2). Coleoptera form a most important ele- 
ment of bird food, the families of this order most largely represented 
being the Scarabaeidse or scarabreid beetles, the Carabida? or ground- 
beetles, the Elaterida3 or click-beetles, the Chrysomelida? or leaf- 
beetles, and the Rhynchophora or weevils. Some of the scarab?eids 
that are eaten are the clumsy brown May-beetles and their allies, 
which feed on growing plants; others comprise 
a group of beetles commonly known as dung- 
beetles, because they subsist on the droppings 
of animals. Ground-beetles are alert, active 
insects, carnivorous in food habits. Click- 
beetles are narrow and hard-shelled; when dis- 
turbed, they curl up and ' play possum ' until 
the danger appears to be past, when they spring 
into the air by spasmodically straightening out 
their bodies with a sharp clicking sound. Their 
larvae, wireworms, are often very destructive 
to crops. The leaf-beetles (see fig. 3) taken by 
birds are pests of little economic importance. 
Weevils (see fig. 4) constitute a destructive class 
of insect pests, and are extensively preyed on. Diptera furnish no sig- 
nificant part of the food of birds, though the slow-moving crane-flies 
(Tipulidse) and midges (Chironomidse) are at times snapped up, and 
some larval Diptera are occasionally eaten. The Hemiptera include 
both leaf -hoppers (Jassida3), which derive their sustenance by probing 
plants with their sucking beaks, and true bugs, which are flat, bad- 
smelling insects. Some of the bugs feed like 
leaf-hoppers on the juices of plants, while 
others are predatory and subsist on succulent 
insects. The hymenopterous element of bird 
food is composed of ants, wasps, and a few 
small bees, the wasps including flower-fertiliz- 
ing species and parasitic species of the families 
Ichneumonidae (see fig. 5), Braconidse, and 
Scoliidse. 
The value of a bird as an insect destroyer 
depends upon the value of the insects it con- 
sumes. Each insect eaten by birds must of 
necessity be injurious, beneficial, or neutral in its effect on crops, 
though it is not always easy to classify it properly. While present 
information is sufficient to fix the status of some with sufficient accu- 
racy for all practical purposes, in the case of others more light is 
needed. The smaller dung-feeding scaraba?id beetles appear to have 
little or no effect upon agriculture. The great majority of ants have 
habits which are apparently of little interest to the agriculturist; 
Fig. 4.— Weevil (after Chit 
tenden: loaned by Divi 
sion of Entomology). 
