INSECTS. 279 
leathery cover — all of which are mandibulate ; and the 
hemvptera^ which have the wings half leathery and half 
membranous, and the mouth suctorial, and in both of the 
latter the metamorphose is imperfect. In the third class 
the wings are naked and alike ; it includes the neuro- 
'ptera^ or nerve-winged insects, in which the veins of the 
wings are like a net ; the hymenoptera, the wings being 
membranous, and veined lengtliwise — both families being 
mandibulate ; the lepidoptera^ or scale-winged insects, 
having delicate scales on the wings — this order is sucto- 
rial, and the entire three orders have four wings ; the 
rhipiptera^ which are mandibulate and have two balances 
or halteres before the wings which close like a fan, 
whence their name is derived, and the diptera^ which have 
two halteres behind the wings — in these families there 
are only two wings. 
The orthoptera include, as familiar examples, cock- 
roaches, crickets, katydids, and grasshoppers ; the neuro- 
ptera white ants, May-flies, caddis-flies, dragon-flies or 
devil's darning needles, and hoodlbugs ; the hymenoptera 
common ants, wasps and bees ; the lepidoptera butter- 
flies, moths, silk- worms, and humming-birds ; the hemi- 
ptera plant lice, cochineals, and locusts ; the diptera mos- 
quitoes, house-flies, horse-flies, and bot-flies. 
The order hemiptera is frequently divided into two, 
according as the wings are of a uniform texture, homo- 
ptera^ or of a varied texture, heteroptera ; the lepidoptera 
are divided into three classes — those that fly by day, and 
generally have the antennae knobbed ; those that fly in 
the twilight and have the antennae thickened, and those 
that are nocturnal and have the antennae slender. The 
