228 THE UNIVERSITY SCIENCE BULLETIN. 
Structural Peculiarities. Wing-pads now long, reaching to the second 
abdominal segment. The hind tarsus is still 1-segmented, and claws re- 
duced. The tibial comb of hind tarsus is composed of longer spines than 
before. The neutrality of the caudal segments of the nymph, in contrast 
to those of the adults, is illustrated in the drawings on plate XXVII. A 
study of specimens killed while emerging shows the marked transforma- 
tion that takes place between nymph and adult. The antenne of nymph 
are heavy blunt-tipped appendages, plainly 2-segmented, with a con- 
striction on the distal segment that may indicate that it is divided into 
two segments. See drawing on plate XXVII. 
Behavior of Adults There are some points in the economy of the - 
lives of these insects worth noting. It is one of the very few water 
insects overwintering as a nymph. In fact, the only one known to the 
writer. For some time it was not clear as to why there should be this 
exception. It seems, however, that since the species seldom, if ever, flies, 
but lives in permanent waters, there is no occasion for the annual fall 
and spring migrations indulged in by other species. Most Corixids fly to 
larger pools to winter and in spring fly back to repopulate the shallower 
ones. 
The adults of this species are given to burying themselves in the floc- 
culent ooze on the bottom of the pool, and are thus difficult to locate. In 
common with other species, they come to the surface for air, and if in 
water of any depth are likely to head downward from the surface, swim- 
ming in a spiral to the bottom. 
In accounts dealing with the stridulation of the male Corixids it is 
stated they make their music at night. Some of these which were brought 
into the laboratory surprised us with their chirping one cloudy afternoon. 
Their stridulation was distinctly audible across the room and sounded 
somewhat like that of distant crickets, save that the chirps came forth 
in couplets. 
Summary. The species here discussed winters as a fourth instar 
nymph, reaches the adult stage about the first of June, and after a matur-— 
ation of eight days begins oviposition. This generation becomes adult 
during August and starts the generation that overwinters as nymphs. 
The species is capable of living in great numbers in a pool. The 
nymphs have been seen to strip the chlorophyll from filaments of Spi- 
rogyra and an examination of the stomachs of many of them shows that 
they consume quantities of living chlorophyll from the lower plant or- 
ganisms that make up the flora of the pool bed. This herbivorous ten- 
a oo 
dency reduces the uncertainty of food getting and accounts in a measure 
for their success. It has further been demonstrated that they can 
complete their life cycle by foraging upon a flocculent mass of ground 
Typha and its attendant population. 
The facts above presented, when combined with the lack of functional 
wings, suggests the practicability of rearing them artificially. Since the 
nymphs of this species have been recovered from the stomachs of fishes, 
it may be that this form, easy to manipulate, can be utilized in increasing 
the food supply for young fish. 
