AQUATIC INSECTS OF FRESHWATER 



ed in the water and the larvse leave the water, burrow into the ground to 

 there undergo the final metamorphosis. The flight of the Diving-beetles 

 is nocturnal and their 

 migrations are from 

 pond to pond, being 

 also attracted by 

 bright surfaces and 

 lights. The com- 

 mon genus is Acilius 



which is about iA_ fig. 223. PredaceousDiving-beetle,^«7«s/>-fl<ernBs. Female and male. Enlarged. 



inch long, of a polished brownish-black color, marked with dull yellow; 

 the elytra covered with fine punctures, the female having four furrows 

 on each wing cover. The more common species are J. fraternus. Fig. 223, 

 and A. mediatus. The largest belong to the Dytiscus, Cybister and allied 

 genera; the former having the cups on the under side of the tarsal discs 



varying in size, and 

 the latter similar and 

 of uniform size. 

 The more common 

 of these are D.fas- 

 civentris. Fig. 224, 

 D. hybridus, and 

 C.fimbriolatus. The 

 genus Colymbetes 

 has the elytra mark- 

 ,. , . . J , ed with numerous 



FIG. 224. Predaceous Diving-beetle, Dydhcus fasci'ventris. Female and male. 



Enlarged. fine ttansversc stria- 



tions. The most common species is C. sculptilis. 

 All are fairly good flyers and widely distributed 

 in almost the entire United States. 



Water-Scavenger Beetles (Great Water- 

 Beetles) belong to the family of Hydrophilidse 

 and closely resemble the Predaceous Diving- 

 beetles in general appearance, but are more 

 convex and have short club-shaped antennae 

 concealed beneath the head and very long 

 palpi, the parts next to the mandables. They 

 are dusky-black beetles of elong-elliptical 

 form, strong, active and of savage disposition. 

 Both the middle and the posterior legs are fringed fig. 225. water scavenger-beetie 



. , , . , - . . 1 •! I or Great Water-beetle, /(j'(/r(i/>A(7as 



With hairs and adapted tor swimming; while the ghher. Male. 



269 



