168 INVERTEBRATE ANIMALS. 
voracious, and every one is acquainted with the terrible ravages 
occasionally caused in hot countries by swarms of locusts. 
The most destructive species is the Migratory Locust (Acry- 
dium migratoritum, fig. 83), which is very abundant in Africa, 
India, and throughout the whole of the East. Owing to the 
rapidity with which they devour everything they can possibly 
’ eat, and owing to their enormous numbers, the Locusts are com- 
pelled to be constantly on the move, looking for “fresh fields and 
pastures new.” It is from these migrations in vast bodies in search 
of food that the Migratory Locust takes its name. When one 
of these destructive hosts visits a district, it only needs a few 
hours to convert the most fertile country into a howling wilder- 
ness. In an incredibly short space of time, every green thing 
Sey 
Pre ee 
Fig. 83.—The Migratory Locust (Acrydium migratorium). 
on their line of march is destroyed, every leaf is stripped from 
every tree, every blade of grass and corn is eaten down, and it 
is not until the ground is utterly bare and brown that the 
locusts take wing and seek out some fresh region to devastate. 
® 
ORDER VI. NEUROPTERA.—The mouth in this order is fitted 
for mastication ; the wings are four in number, generally nearly 
equal in size, all membranous, and traversed by numerous 
delicate nervures, which interlace so as to form a delicate net- 
work (fig. 84). The metamorphosis is generally incomplete, but 
is sometimes complete. 
This order includes the well-known and rapacious Dragon- 
flies (Lzbellulide), the Caddis-flies (Phryganeide), the May-flies 
(Ephemeride), the Ant-lion (Myrmeleo), the Aphis-lion (fig. 84), 
Termites, &c. The last of these—namely, the Termites or white 
ants (fig. 85)—are social insects, living in organised communities, 
