Abstract
One of us 1 has shown that the variations in the hypodermal color pattern of the stink-bug Perillus bioculatus (Fab.) from white and black to red and black (with various intermediate yellow and black forms) are not caused by inheritance but by variations in physiological activity, which can be controlled by the temperature of the environment, and influenced by sexual functions, such as egg laying. The food of the stinkbug is always highly colored with orange-yellow pigment for it consists almost exclusively of the eggs and larvae of the potato beetle, Leptinotarsa decemlineata (Say), as well as the adult beetle itself. When the larvae and adult beetles are attacked the golden yellow lymph is the only portion eaten.
A chemical examination of the pigment in the lymph of the potato beetle showed that it consists exclusively of carotin. No other carotinoids could be detected. The concentration of carotin in fresh lymph obtained from 200 full-grown larvae was found to be 0.0136 per cent, which is as high as is encountered in fresh green leaves.
The red and yellow colors in the hypodermis of the stink-bug were also found to be due to carotin. Some water-soluble substance yielding yellow solutions was also present in the hypodermis, but it is doubtful whether it contributed greatly to the color pattern.
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