308 ENTOMOLOGY 
The Myrmeleon larva digs a funnel-shaped pitfall, at the bot- 
tom of which it buries itself to await the fall of some unlucky 
ant. The Chrysopa larva impales an aphid on the points of 
its mandibles and sucks the blood through a groove along 
each mandible (Fig. 45, &), the maxilla fitting against this 
groove to form a closed channel. Several families of Coleop- 
tera are almost entirely predaceous. Among aquatic beetles, 
Dytiscidze are carnivorous both as larvee and imagines, Gyrin- 
idze subsist chiefly upon disabled insects, but occasionally eat 
plant substances, and Hydrophilidz as larvee catch and devour 
other insects, though some of the beetles of this family (H. 
triangularis, for example, lig. 226) feed largely if not en- 
tirely upon vegetation. Of terrestrial Coleoptera, the tiger 
beetles ( Cicindelidze ) are strictly predaceous upon other insects. 
The Cicindela larva lives in a burrow in the soil and lies in 
wait for passing insects; a pair of hooks on the fifth segment 
of the abdomen serves to prevent the larva from being jerked 
out of its burrow by the struggles of its captive. The large 
family Carabide is chiefly predaceous; these ‘ running 
beetles ” both as larvee and adults easily overtake and capture 
other terrestrial insects. The Carabidz, however, are by no 
means exclusively carnivorous, for many of them feed to some 
extent upon fungus spores, pollen, ovules, root-tips and other 
vegetable matter, as Forbes has found; Harpalus caliginosus 
eats the pollen of the ragweed in autumn; Galerita janus eats 
caterpillars and occasionally the seeds of grasses; Calosoma, 
however, appears to be strictly carnivorous, feeding chiefly 
upon caterpillars and being in this respect of considerable eco- 
nomic importance. As a whole, Carabidze prefer animal food, 
as appears from the fact that when canker worms, for in- 
stance, are unusually abundant they form a correspondingly 
large percentage of carabid food, the increase being compen- 
sated by a diminution in the amount of vegetable food taken 
(Forbes). Coceinellid larvae (excepting Epilachna, which 
eats leaves) feed almost entirely upon plant lice and consti- 
tute one of the most effective checks upon their multiplication ; 
