PROTECTIVE DEVICES 



53 



The formic acid and the other toxic elements pmbably 

 present in the fluid ejected from the glands of the body 

 of the attacking bee, while discomfiting to us, are quite 

 deadly to the bees. This poisonous fluid can be secret r. I 

 from the blood-cells of the bees, but when it is injected 



FIG. 426. Pupa-case of black swallowtail butterfly on white saucer, side view, 

 showing protective resemblance in coloration of the pupa-case to the white saucer. 

 Natural size. Photographed from life. 



FIG. 43. The bombardier beetle (Brachynus 

 americanus). Enlarged three times. 



In, .44. The "stink-bug" 

 (Podisus spinosus). Ren- 

 dered distasteful to birds 

 by its ability to give off an 

 offensive odor. Enlarged 

 about two and one-lui'f 

 times. 



