90 



THE STUDY OF INSECTS, 



and a strong cross-vein. This structure resembles in ap- 

 pearance a joint, and is consequently named the nodus. 



The mouth-parts are fitted for biting, these 'insects being 

 voracious feeders in the adult state. Both the upper lip and 

 the lower lip are large, and the two nearly enclose the jaws 



Fig. 98. — Agrion, 



Fig. 99. — Nymph of Dragon-fly, 

 Agrionince, 



when at rest. There are two distinct types of Dragon-flies : 

 in one the wings are extended horizontally when at rest 

 (Fig. 97) ; in the other the wings are folded together above 

 the abdomen when not in use (Fig. 98). 

 This order includes only a single family. 



Family LlBELLULlD^ (Lib-el-lu'li-dae) 



The Dragon-flies. 



Darning-needles, Devil's-needles, Snake-doctors, Spindles, 

 and Dragon-flies are some of the names given to those in- 

 sects which dart back and forth over streams and wet places. 



