278 Annals Entomological Society of America  [Vol. XIV, 
berg (1915a, p. 402), responds quickly to a moving object or to 
a shadow. As early as the summer of 1911, it was observed 
by me (1920, p. 70) that Gerris remigis evinces responses to 
moving objects and shadows. Some years later, the behavior 
of this species with respect to a moving incandescent light 
of 44 ca. m. in the experimental field was noticed. The following 
quotation gives my statement: 
I observed, as early as the summer of 1911, that these water-striders 
[Gerris remigis] respond to moving objects and shadows more promptly 
than they do to stationary ones. In the early fall of 1918, I discovered 
that individuals of Gerris remigis, confined in an aquarium, respond 
definitely and in a pronounced manner to a moving incandescent electric 
light and also to frequent changes in the position of such a light. 
It is very probable that photic responses form an important 
part of the general behavior of the family Gerridz. Therefore, 
at this point it is, perhaps, worth while to draw attention briefly 
to some of the records of various writers on this group. State- 
ments by Kirkaldy (1898, p. 110) indicate that Gerris thoracicus 
Schumn, in Hungary and Gerris tristan Kirk., in Ceylon are 
both positively phototactic at night. Weiss (1914, p. 33), in 
certain experiments with water-striders, Gerris marginatus, a 
species related to and frequently observed in similar situations 
as Gerris remigis, found that, when they were removed from 
the surface of a large pond and placed on the ground at distances 
of one to nine yards from their habitat, they returned to the 
water promptly. It is quite possible that vision was the most 
important factor in guiding these insects back again to the 
water. The pool referred to by this observer covered an area 
of 3,000 square feet and would therefore serve as an effective 
reflective surface. According to Essenberg (1915a, p. 400), 
Gerris orba, a species closely related to and sometimes mistaken 
for Gerris remigis, exhibits positive phototaxis, sometimes 
leaving the surface of the water and flying to the light. Several 
years ago, while conducting an extended series of observations 
and experiments on some habitat responses of Gerris remigis, 
certain phases of the behavior of this species indicated that 
vision played a not inconsiderable rédle. In this connection 
reference is suggested to some of my former papers (1919, pp. 
410-414), (1919a, pp. 503-505), (1920, pp. 68-70, 71-72, 77-80), 
(1920a, p. 9). It was suggested by me (1919a, p. 499) that 
Gerris marginatus, another common species of water-strider, 
