STUDIES ON PERILLUS BIOCULATUS FAB. 81 
Nature of the Color Pattern 
As stated briefly in the introduction, the writer began his studies 
on Perillus with the idea of working on color inheritance in this 
insect. After three seasons of breeding work trying to establish pure ~ 
lines of the white color form, and of a red color form, it became 
perfectly clear that the color pattern of individual bugs was influenced 
more by conditions under which they were reared than by characters 
inherited from the parents. Since that time breeding experiments 
have been carried on with the purpose of determining those factors 
which produce the white color form, as well as the other extreme, 
the red color form. It is hoped to publish elsewhere a more detailed 
account of these experiments, but at the present time it is desired to 
make a few preliminary statements of the resuits which will better 
explain the nature of color varieties in Perillus and other Heteroptera. 
The principal types of coloration found in insects have been dealt 
with in a comprehensive paper by Hagen (1883). Hagen reviews all 
the published statements regarding the nature of color in insects and 
then contributes much from his own researches. This author divides 
insect colors into: (1) dermal or cuticula colors; (2) hypodermal 
colors. Tower (1903) published additional data, especially through 
morphological studies on the hypodermis and cuticular layers. The 
present writer has made morphological studies on the body wall of 
Perillus and finds much in common with the figures published by 
Tower, exhibiting details of the hypodermis and cuticula of Coleoptera. 
The present studies on Perillus show that the black and brown 
colors are located in the cuticula and are not subject to change, once 
the adult stage has been attained. The white, yellow, and red colors 
are located in the hypodermis and show through where black color- 
ing matter is not present in the cuticula. The white color oecurs in 
the absence of pigment granules in the hypodermal cells, while in the 
yellow and red varieties the hypodermal cells are filled to a greater 
or less degree with minute colored granules. The writer’s breeding 
experiments with Perillus show that the accumulation of pigment gran- 
ules in the hypodermis is influenced largely if not entirely by the 
_ physiological activities of the bug. And the physiological activities of 
the bug are governed very largely by the temperatures to which it 1s 
subjected. With some insects the kind of food taken would be ex- 
pected to influence the color, but in the case of Perillus the food uni- 
formly consists of body fluids.of potato beetles and their larvae. 
