INSECTS. 279 



leathery cover — all of which are raandibulate ; 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 lengthwise — 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 

 rhipipt&ra, 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 orthojptera include, as familiar examples, cock- 

 roaches, crickets, katydids, and grasshoppers ; the nev/ro- 

 ptera white ants, May-flies, caddis-flies, dragon-flies or 

 devil's darning needles, and hoodlbugs ; the hym&rvoptera 

 common ants, wasps and bees ; the lepidoptera butter- 

 flies, moths, silk-worms, and humming-birds ; the hemi- 

 ptera plant lice, cochineals, and locusts ; the di/ptera mos- 

 quitoes, house-flies, horse-flies, and bot-flies. 



The order Kemvptera 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 aocturnal and iave the antennae slender. The 



