TWO-WINGED INSECTS. 293 



are divided into two sections Land-bugs and Water- 

 bugs. To the former section belong the Bedbugs be- 

 fore referred to. Of the Water-bugs there are only two 

 families the Boat-flies and the Water Scorpions. The 

 former are good swimmers, always swimming on the 

 back. They can fly well, but rarely do it. 



499. The Diptera, or two- winged insects, constitute 

 one of the most extensive orders, both in the number of 

 species and in the number of individuals. None of them 

 are large, and some are exceedingly small. For the most 

 part they are dull in color. On the head are two very 

 large compound eyes, and two short antenna? near to- 

 gether. In some there is a soft proboscis, as the com- 

 mon House-fly; in others, a hard, pointed, sucking tube, 

 as in the Musquito ; and in others still, simply a mouth. 

 They have three pairs of feet, and two thin wings, which, 

 in most cases, give out a humming sound in flying. 

 Their larva? are generally maggots, white, and having 

 no feet, but instead thereof fleshy tubercles or warts, on 

 which they crawl. Most of the larvae live in dirt, or 

 dung-hills, or spoiled meat, or cheese, etc. The meta- 

 morphosis is complete, but in some cases very peculiar. 



500. The species of Flies are very numerous. There 

 are about seventeen hundred known in Europe. The 

 larva? of Flies, the maggots, generally live in some kind 

 of filth ; but the Flies themselves live, for the most part, 

 on dainty food. The wing of a common Fly, examined 

 under the microscope, is a beautiful object. Although to 

 the naked eye it has a very plain appearance, it is cover- 

 ed with little pointed projections of curious shape regu- 

 larly arranged. 



501. The larvae found in cheese come from eggs depos- 

 ited by a small Fly. From their great power in leaping 

 they are called Cheese-hoppers. The manner in which 

 the leap is performed is very singular, and is thus de- 

 scribed by Carpenter : " When preparing to leap, it first 

 raises itself upon its tail, in which position it is enabled 



