CLASSIFICATION 109 



flies and skippers are active during the day, that is, they are 

 diurnal, and the moths at night (nocturnal). The members of 

 the three main groups can be distinguished by their antennae; 

 those of the butterflies end in a knob, of the skippers in a knob 

 with a recurved point, and of the moths without the knob but 

 often with bristles on the sides. 



Order 6. Diptera. — House Flies, Mosquitoes, etc. 

 Insects with the two fore wings present, but the two hind 

 wings represented by knobs; sucking mouth parts; metamor- 

 phosis indirect. 



Some of the Diptera are degenerate and without wings, such 

 as the bird lice, fleas, and sheep tick; the winged species include 

 the house flies, mosquitoes, crane flies, midges, gnats, horse 

 flies, botflies, and flower flies. 



Order 7. Coleoptera. — Beetles. 



Insects with four wings, the fore wings (called elytra) sheath- 

 like and covering the membranous hind wings; biting mouth 

 parts ; metamorphosis indirect. 



This is a very large order in number of species. Some of the 

 common families are the tiger beetles, ground beetles, whirligig 

 beetles, burying beetles, click beetles, scarabid beetles, June 

 bugs, potato beetles, ladybird beetles, bark beetles, weevils, 

 meal-worm beetles, Spanish flies, and fireflies. 



Order 8. Hymenoptera. — Ants, Bees, Wasps, etc. 

 Insects with four membranous wings; mouth parts both for 

 biting and sucking; sting often present; metamorphosis in- 

 direct. 



This is another very large order. Some of the principal fam- 

 ilies are the ants, bees, wasps, sawflies, gallflies, ichneumon 

 flies, and chalcid flies. 



It is evident from the above list that in many cases one could 

 not tell from the common names where the insects belong. For 

 example, the true flies are the Diptera, but some of the members 

 of almost every other order are called flies, such as the May flies, 

 butterflies, fireflies, and sawflies. To most people an insect 



