AQUATIC INSECTS 



as far as the striders themselves. Water-mites lay their 

 eggs on aquatic plants and their six-legged larvae hatch out, 

 soon fastening themselves to water-insects by means of their 

 hooked mouth parts. Their heads work deeper and deeper 

 into an insect's body, their legs curl up and finally only the 

 scarlet bag-like body shows on the outside (p. 176). Within 

 this bag the six-legged larva transforms and finally emerges 

 as a free-swimming eight -legged mite. 



Fig. 173, — Large water strider, Gerris remigis, 



adult. 



Large water strider, Gerris remigis. — Unlike the next species 

 these water striders have dark under surfaces, and the adults 

 (Fig. 173) are usually wingless. They seem to prefer clear 

 running streams where they gather beside the tree trunks, 

 and in quiet places near bends in the shore. They cannot 

 migrate except by jumping and many of them are caught in 

 isolated pools and die there when the water dries up in sum- 

 mer. Both adults and young are parasitized by water-mites. 

 Adults, one half inch long. 



Occurrence. — Common from Labrador to Mexico. 



Gerris conformis. — The adults of Gerris conformis are al- 

 ways winged and slender and the underside of their bodies 



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