HEMIP TER A. 
135 
est across the prothorax. These Broad-shouldered Water- 
striders constitute the family Veliidce . 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 156 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. 15 7 .-Hygrotrechu S con/orntis. themselves away under the 
banks or at the bottom of the water, and do not come to 
