
AQUATIC INSECTS OF FRESHWATER 

with peculiar jointed antenne, strong mandables and 
eyes divided by the margins of the head, so that 
they appear to have eyes for looking into the air 
and a second pair for seeing into the water. The 
body is of slightly flattened oval or elliptical form, 
the anterior legs very long and the middle and pos- 
terior legs short, broad and flattened. ‘The breath- 
ing apparatus is located at the sides and back of the 

abdomen. Small cylindrical eggs are laid in parallel 
rows upon aquatic plants, and the larve are narrow, — gy¢. he Whirligig-beetle, 
flat and long, somewhat resembling centipedes. Gyrinus affinis, Enlarged, 
Each abdominal segment is furnished with gills and the caudal end has a 
pair of breathing tubes. Fig.229. When fully developed the larva leaves the 
water to spin a cocoon onsome near by Nee 
object, in which it passes the pupal 
stage and emerges in about one month 
as the fully developed beetle. The  ~*= 
4 : 
food of the larva consists of the 7% 
smaller water animals; that of the ARS 

beetle of flies and other insects, small MES 
tadpolesand young fishes. The mouth TES 
= LO 
parts of the beetle are developed for “7 
FIG. 228. Whirligig-beetle, biting and can inflict stinging and ap 
pa ee tnkect bleeding wounds. “Whey arevery agile ae. a Fe ae 
swimmers, their peculiar gyrations on the water having geen 
earned for them both their scientific and popular names. Enlarged. 
There are three generally distributed genera, Gyretes, of which the most 
common species is G. simatus; Gyrinus, of which G. rockinghamensis and 
G. affinis, Fig. 227, are most generally distributed; and Dineutus, of 
which D. vittatus, Fig. 228, and D. assimelis are the more generally 
distributed forms in the Eastern and Middle States. 
: Ponp-BeEeETLeEs OR Hatip.ips are small beetles 
belonging to the large family of Haliplide, having 
oval bodies more or less pointed at each end; the 
three most generally distributed aquatic genera be- 
ing Brychius of the Pacific Coast States, and Hall- 
plus and Cnemidotus, common to almost all ponds 
and streams on the Atlantic slope. The larve are 
aquatic and have a slender segmental body furnished 

FIG. 230. Pond-beetle or : : : - 
Haliplid, Haliplus rufcollis, With spiny tips, the last segment bearing a long 
Greatly enlarged. 
single or forked caudal appendage. The most 
271 
