Sept., i924.i Colors of Bugs. 163 



THE COLORS OF BUGS 



Two papers by Leroy S. Palmer and Harry H. Knight on the 

 colors of bugs have recently appeared in the "Journal of Biological 

 Chemistry" (Vol. LIX, No. 2, March, 1924, pp. 443-449; pp. 

 451-455). These authors, after a chemical study, conclude that 

 "the yellow and red colors seen in the hypodermis of the stink-bug, 

 Perillus biociilatus (Fab.), are due largely to carotin which is 

 derived from the food ; namely, chiefly the lymph of the potato 

 beetle, Lcptinotarsa dccemlincata (Say)," and state that the lymph 

 of the potato beetle is colored entirely by carotin, the concentration 

 in fresh lymph being as high as that found in fresh green leaves. 

 Carotin has been defined as a ruby red crystalline substance found 

 in the chromoplasts in various plants especially the carrot. 



The authors made chemical examinations of the red pigment in 

 other bugs and found that it was not limited to one type of sub- 

 stance but that "water soluble pigments appear to be more com- 

 mon than carotin." They report that the vermilion color of the 

 aphid Tritogcnaphis rudhcckicu (Fitch) is due chiefly to an antho- 

 cyanin-like pigment although small amounts of carotin are pres- 

 ent. Anthocyanin is a coloring matter found in the cell sap of 

 many plants and is red in the presence of acids. The red color of 

 the red and black plant-bugs Lcptocoris trivittatus Say, Lygccus 

 kolrnii Stal. Lopidca stapJiylcac Kngt., Cod^obapJics sauguinareiis 

 Uhler and the assassin-bug Eidyes illiisfris Stal was found to be 

 due to a flavone-like pigment. Flavone is the parent substance of 

 a large number of yellow dyestuft's. 



Palmer and Knight state that it is difficult to "understand how 

 environment can cause a permanent modification of an insect color 

 pattern involving an animal pigment which is derived from the 

 food, and which is subject to fundamental physiological processes 

 of the protoplasm without first causing a permanent modification 

 of the processes to which the derived pigment is subject" and 

 believe that the claim that red pigment in insects can be so changed 

 and the changes become inheritable loses weight in view of the 

 findings that the pigment is likely to be one of the previously 

 mentioned substances derived from the food. 



