(x JAN 28 1922 
- 
x 
1921] Riley: Responses of Water-Simdationa) Mvs® 
At this point it may be mentioned that a number of other 
entomologists have referred to the hibernation quarters of 
water-striders. Among these are Uhler (1884), McCook (1907), 
and Kellogg (1908). From the context, it is to be inferred 
that all three of these writers refer to Gerris (= Hygrotrechus) 
remigis. Uhler (1884, p. 268) makes the statement that: 
These insects stow themselves away under the banks of streams, in 
the mud beneath leaves or rubbish, or at the bottom of water under 
stones and roots of trees when the autumn begins to be cold, and from 
thence they reappear upon the surface of the water as soon as the 
warm weather of spring returns. 
McCook (1907, p. 265), when writing about the hibernation 
of water-striders, remarks that: 
When winter sets in the survivors of the season burrow into the 
mud, or under bunches of dead leaves and withered grass-stalks or 
stones or other rubbish, and there lie dormant or semidormant until 
spring again calls them to active life. 
Kellogg (1908, p. 198), in referring to the situations in which 
water-striders hibernate, makes the following statement: 
In late autumn the water-striders conceal themselves in the mud 
beneath leaves or rubbish or at the bottom of the pool under roots or 
stones to hibernate, coming out again with the first warm days of spring. 
I wish to state that it was a long time before I found Gerris 
remigis in a hibernating condition. Search was made in almost 
every conceivable situation before the hibernation quarters 
of this species were located. Many careful searches were con- 
ducted during a large part of one winter before any hibernating 
individuals were ‘discovered, and a part of a second winter 
passed before they were found in numbers. For a period of 
years, both in the autumns and in the winters, careful observa- 
tions were made of the behavior of these water-striders, not 
only as they migrated into places of hibernation, but also after 
they were settled in their winter quarters (Figs. 5, 6, 7, 8, 9, 10); 
and I never have found them hibernating in mud, in water, 
at the bottom of water, at the bottom of a pool, pond, brook, 
creek, or river. 
During the hibernating period, the gerrids evince little 
movement. Within a radius of two miles of White Heath, 
Illinois, in the months of December and January, large numbers 
have been taken from holes in the banks of brooks—but not 
