THE REFLEX "BLEEDING" OF THE COCCINELLID 

 BEETLE, EPILACHNA BOREALIS. 



N. E. McIndoo, Ph. D., 

 Bureau of Entomology, Washington, D. C. 



INTRODUCTION. 



It is a well-known fact among entomologists that when 

 disturbed certain coccinelHd and meloid beetles fold the antennae 

 and legs against the body, eject small drops of liquid from the 

 femoro-tibial articulations and feign death. There has been 

 quite a controversy as to how the liquid is expelled so quickly 

 and as to whether the liquid is blood or is a glandular secretion. 

 Those who believe that the liquid is blood fail to show how it 

 passes through the articular membrane to the exterior, and 

 those who think that the liquid is a glandular secretion do not 

 conclusively prove their view and. they fail to explain how such 

 a large quantity of the secretion can be expelled so quickly. 



The phenomenon of ejecting Hquid from the femoro-tibial 

 articulations has been called "reflex bleeding." The object of 

 the present paper is to show that the phenomenon is a true 

 reflex, but that instead of the liquid being blood, it is a secretion 

 from hypodermal glands and that it passes to the exterior 

 through innumerable tubes opening near and in the articular 

 membrane. 



To obtain material for sections, adult beetles that had been 

 kept in the laboratory all summer were mostly used, although 

 two beetles emerged a short time were also used. Most of the 

 sections were cut five microns in thickness, and all of them were 

 stained with Ehrlich's hematoxylin and eosin. In regard to 

 more details concerning the technique, the reader is referred to 

 the writer's work (1915) on "The Olfactory Sense of Coleoptera." 



EXAMINATION OF LIVE BEETLES. . 



When live individuals of Epilachna burealis are examined 

 without irritation under a low-power lens, they appear wet. 

 The more the beetles are irritated the wetter their integuments 

 become. The entire chitinous integument is more or less cov- 

 ered with small yellow flakes. On the legs and elytra these 

 flakes are numerous, and they may be easily removed with a 

 needle. Beetles in the field eject small drops of liquid from the 



