AQUATIC INSECTS OF FRESHWATER 



FIG. 199. Water-scorpion, 

 Ranatrafusca, Enlarged. 



monary functions. The insect rests on the stalks of plants or slowly 

 moves over the bottom and is difficult to observe on account of its form 

 and the mud on the body. It is a weak flyer and 

 only migrates when the pool is dry and in the 

 mating season. Food largely consists of the eggs 

 of fishes, frogs, snails and insects, but it will 

 prey upon other water inhabitants and on young 

 tadpoles and fishes. The most generally dis- 

 tributed species are N. apiculata. Fig. 198, R. 

 fusca. Fig. 199, and R. quadridentata. 



Giant Water-Bugs belong to ,the family 

 of Belostomatidae, are all strictly aquatic and are 

 most dangerous to spawn and young fishes, as 

 they are predatory, live on the bottom and feed 

 on aquatic animals. In the Eastern section of 

 the United States the common forms of these 

 bugs belong to the genera Belostoma, Benucus 

 and Zaitha; of which the first named are the 

 largest and are of elongated oval outline, very flat 

 with almost transparent wings of greyish or brownish color. Benucus is 

 almost as large and may be distinguished by the absence of the double 



groove on the under side of the fore thighs, 

 which is characteristic of the first named. 

 But one species of Benucus, B. halder- 

 manum, is found in the United States. 

 The form in Zaitha is like the foregoing 

 but the species are smaller. Belostoma 

 are abundant in the tropical and temperate 

 zones of America, a tropical species, B. 

 grande, reaching a length of four inches ■ 

 and B. griseum. Fig. 200, the largest of 

 the United States attains a length of three 

 inches. Their general color is greyish, 

 FIG. 200. Giant Water-bug, Be/oaoOTa^mraffl. yellowish or grccnish-brown but they are 

 usually covered with mud and when wet are darker in color than in the 

 specimen cabinet. The anterior legs are strongly developed to seize their 

 prey and the oarshaped posterior legs for swimming. When fully devel- 

 oped they have strong wings capable of long sustained flight, which takes 

 place at night, and enables them to seek other ponds and water courses 

 when theirs dry out. They are often found in cities, their defective sight 

 leading them to mistake large reflecting surfaces, like skylights and green- 



254 



