INSECTS. 



247 



(ODONATA); their larvae live in the water, where they 

 feed upon other insects, etc., and especially on the larvae 

 of mosquitoes. When the adult stage is reached and they 

 take to the air, they are veritable dragons, feeding upon 

 insects, which they catch on the wing. Here, too, belong 

 the May-flies or day-flies with an aquatic life of from one 

 to three years, a life in the air of but a few days, or even a 

 few hours. These May-flies often appear in great numbers 

 in the cities near the Great Lakes. 



The celebrated white ants or termites (fig. 71) may 

 represent the forms with a solely terrestrial life-history. 

 These are not ants at all in the true sense of the word, but 



FIG. 71. White ant (Tertnes flavipes). a, larva; b, winged male; c, worker; 

 d, soldier; e, queen; /, pupa. From Riley. 



they resemble them in several points. They form large 

 colonies consisting of several distinct ' castes ' with different 

 structure. Only the kings and queens are winged, and only 

 these are capable of reproduction. Besides these there 

 are 'workers' and 'soldiers.' The workers build the 

 nests, gather the food for the whole colony, and bring 



