HEMIPTERA. 135 



est across the prothorax. These Broad-shouldered Water- 

 striders constitute the family Veliida;. They pass the greater 

 part of their lives upon the surface of the water, often con- 

 gregating in schools containing hundreds of individuals ; but 

 they usually remain near the banks of the stream or pond, 

 and sometimes they leave the water, mov- 

 ing on the land with great freedom. Like 

 the members of the allied families, they are 

 predaceous. Figure 1 56 represents one of 

 these insects somewhat enlarged. 



FIG. 156. Rhagovelia 

 collaris. 



Family HYDROBATID^E (Hyd-ro-bat'i-dae). 

 The Water-striders. 



On the quiet pools of a running stream or the calm 

 waters of a protected pond may be found swarms of slender 

 long-legged insects that seem to find the water surface a 

 pavement well suited for their airy feet. If your approach 

 is stealthy you may see them resting motionless as if ab- 

 sorbed in gazing at their own reflections in the mirror below 

 them ; but disturb them, and so swiftly do they move 

 that they seem but darting lines as they circle around and 

 around each other in a mystic dance. If you watch them 

 closely you may see one leap into the air after some approach- 

 ing insect. 



These are the true Water-striders. In some of them the 



body is long and narrow, as 

 shown in Figure 157; in 

 others it is oval ; but in all 

 it is widest back of the pro- 

 thorax, thus differing from 

 the form seen in the pre- 

 ceding family. 



In the winter they stow 



FIG. icy. Hygrotrechus conformis. .1 i 1^1 



themselves away under the 

 banks or at the bottom of the water, and do not come to 



