ARTHROPODA. 
297 
are Crickets ( Gryllus), Locusts (. Locusta ), Grasshoppers 
(. Acrydium ), Walking- sticks (. Phasma), and Cockroaches 
(. Blatta ). 
3. Hemiptera, or “ Bugs,” are chiefly characterized by 
a suctorial mouth, which is produced into a long, hard, 
beak, in which mandibles and maxillae are modified into 
bristles and enclosed by the labium. The four wings are 
irregularly and sparsely veined, sometimes wanting. The 
body is flat above, and the legs slender. The larva differs 
from the imago in wanting wings. In some species the 
fore-wings are opaque at the base and transparent at 
the apex, whence the name of the order. Some feed on 
the juices of animals, others on plants. Here belong the 
wingless Bed-bug ( Cimex ) and Louse ( Pediculus ), the 
Squash-bug (Coreus), Water-boatman ( Notonecta ), Seven¬ 
teen-year Locust (Cicada), Cochineal (Coccus), and Plant- 
louse (Aphis). 
4. Coleoptera, or “ Beetles.” This is the largest of the 
orders, the species numbering about ninety thousand. 
They are easily recognized by the elytra, or thickened, 
Fio. 267.—a, imago, and b, larva, of the Goldsmith Beetle (Cotalpa lanigera ); c, 
pupa of June-bug ( Lachno&terna fmca). 
horny fore-wings, which are not used for flight, but serve 
to cover the hind pair. When in repose, these elytra are 
always united by a straight edge along the whole length. 
The hind wings, when not in use, are folded transversely. 
