THE FLY. 



The big bnzzing " bine-bottle," or ao; of the oommon flies fonnd 

 abont hoaaes, can be need for this lesson, thongh the green-headed 

 horse-fly (Fig. 1) is better, if it can be obtained. Most of the de- 

 scriptions here given will apply to either of these. The crane-flies 

 with their delicate wings and long, slender bodies, are also invaln- 

 able as specimens. 



The fly is an insect. It has a short, broad body. It 

 has head, thorax, and abdomen. It has three pairs of 

 legs. It has one pair of wings and one pair of balancers 



Fig. 1. 



The last statement can be made only after carefnl observation. 

 The little scale or winglet on each side (Fig. 2, sc) will at first be 

 taken for another wing, bnt after drawing the wing forward several 

 times we discover that the winglet moves with it and must be h 

 part of it. Hence there can be bat one pair of wings. Jnst nnder 

 the wingleta is a pair of tiny whitish knobs on slender stems (Fig. 

 3, tv") known as the balancers. 



Fig. 2 represents the second ring of the thorax of the horse-fly, 

 and Fig. 3 the third ring, with the appendagee of one side. The 

 balancers, being the greatly reduced second pair of wings, are borne 

 on the third thoracic ring. 



106 



