INSECT SUCKERS AND BITERS. 209 
In any pond in the summer time you may see 
ihese agile insects rowing themselves along, under-side 
uppermost, by their two long hind legs, and poking 
their tails out of the water to take in air under their 
wings. Then as they row themselves down again you 
can see bubble after bubble escaping from the tail till 
they come up for more. You might think they were 
water-beetles, but their strong wings which they use 
to leave their ponds by night are all four made use 
of in flying, whereas in beetles the two front wings are 
only stiff covers to preserve the delicate ones under- 
neath. Moreover, these bugs have the same lancet 
mouths as the plant-lice, with which they pierce the 
skins of the tadpoles, soft grubs, and other water 
animals near the bottom of the pond and suck out 
their bodies, leaving nothing but the empty film-like 
skins. They are most voracious animals and will 
attack even small fish. Their habit of moving up- 
side down is of great use to them in feeding, for 
many of their victims have hard backs, so the water- 
boatmen dive down and come up under their prey, 
thus attacking them on their soft side. 
Thus we see that the sucking lice and bugs with 
their beak-like mouths have bored their way into all 
kinds of living food ; into plants, shrubs, and trees in 
all countries, and into the flesh of men and animals 
both on the land and in the water, for many of 
the lice on birds and other creatures belong to this 
class* 
And yet in spite of their numbers they are not 
nearly so destructive as the next class of insects we 
* Called Eemiptera, or half-winged {hernia half; pteron, wing). 
