34 THE UNIVERSITY SCIENCE BULLETIN. 
noted, however, deal in large measure with their prowess in 
mastering insects and other animals larger than themselves. 
- Thus the textbooks on Entomology state the the aquatic Hemip- 
tera are without exception, predatory. Weare led to believe that 
those which dwell upon the surface lead a precarious existence, 
subsisting upon such uncertain fare as the accidents of nature 
may provide. In other words, that their food supply consists 
in the capture of such flies and other terrestrial insects as may 
chance to fall into the water. One writer in fact has stated 
that Gerris shows no response to forms meeting the surface 
film from below. This, however is not in keeping with the 
frequent observation that Gerris will strike for a back-swim- 
mer nymph that comes to the surface close by. 
The writer has pointed out that the food of our common 
water-strider Gerris marginatus consists at certain times of 
the year almost exclusively of the Cicadellids (Jassids) and 
related forms that feed on Juncus and spike rush, bordering 
on and growing in the shallow waters. In checking over the 
field notes on the feeding habits of these insects, it is seen that 
much of their food is produced close at hand, both within and 
about the pool. So, also, with the “toad-bug” Gelastocoris ocu- 
latus, which has been taken feeding upon lace bugs (Tingi- 
didx) reared close by. 
Our common species of Rheumatobates, while it does not — 
disdain to feed upon small insects that fall into the water, ob- 
tains its main supply from the little crustacean forms such as 
Ostracods and Daphnians which swarm the quiet pools. These 
it captures as they rest at the surface, scooping them out and 
holding them aloft upon the upturned tip of the beak, while the 
body of the little victim is being depleted of its nutritive ma- 
terial. 
The little Microvelia borealis, common in Kansas, has access 
to the same source for its food supply and similar habits of 
consuming it. Mesovelia mulsanti has been observed exploring 
the sides of stems of rush and cattail that floated upon the sur- 
face for Ostracods, which it occasionally obtained, while Hydro- 
metra martini stalks about over the floating vegetation in 
search of whatever small beings chance to come to the surface 
film. Its victims have been observed to consist of mosquito 
wrigglers, mosquito pup, emerging midges, nymphal Corixids, 
and Ostracods, as well as small terrestrial insects floundering 
on the water. 
