States have scarcely
begun their work of destruction, as the buds do not unfold before the
first of May. We give an account, however, of some of the beneficial
insects which are now to be found in grass-lands and in gardens. The
farmer should know his true insect friends as well as his insect foes.
We introduce to our readers a large family of ground-beetles (Carabidae,
from Carabus, the name of the typical genus) which prey on those insects
largely injurious to crops. A study of the figures will familiarize our
readers with the principal forms. They are dark-colored, brown or black,
with metallic hues, and are seen in spring and throughout the summer,
running in grass, or lurking under stones and sticks in damp places,
whence they sally forth to hunt by night, when many vegetable-eating
insects are most active.

[Illustration: 219. Calosoma scrutator.]

[Illustration: 220. Calosoma calidum and Larva.]

The larvae are found in much the same situations as the mature beetles.
They are, elongate, oblong, and rather broad, the terminal ring of the
body being armed with two horny hooks, and having a single fleshy leg
beneath; and are usually black in color. The larva of Calosoma (C.
calidum, Fig. 220; _a_, the beetle; and Fig. 219, C. scrutator) ascends
trees to feed on caterpillars, such as the Canker worm. When about to
transform to the pupa state, it forms a rude cocoon in the earth. The
beetle lies in wait for its prey in shallow pits excavated in pastures.
We once saw it fiercely attack a May beetle (Lachnosterna fusca) nearly
twice its size; it tore open the hard sides of its clumsy and helpless
victim with tiger-like ferocity. Carabus (Fig. 221, C. serratus Say, and
pupa of Carabus auronitens of Europe, after Westwood) is a closely
allied form, with very similar habits.

[Illustration: 221. Carabus and Pupa.]

[Illustration: 222. Brachinus.]

[Illustration: 223. Casnonia.]

[Illustration: 224. Pangus.]

[Illustration: 225. Agonum.]

[Illustration: 226. Carabid Larva.]

A much smaller form is the curious Bombardier beetle, Brachinus (Fig.
222, B. fumans), with its narrow head and heart-shaped prothorax. It is
remarkable for discharging with quite an explosion from the end of its
body a pungent fluid, probably as a protection against its enemies. An
allied genus is Casnonia (Fig. 223, C. Pensylvanica), which has a long
neck and spotted wing covers. Figure 224, Pangus caliginosus, and figure
225, Agonum cupr