152 PROC. ENT. SOC. WASH-., VOL. 20, NO. 7, OCT., 1918 



If the extermination of an injurious insect were ever possible, 

 one would suppose the conditions in Dickinson are most favor- 

 able. The individuals of the pest are large, their range is limited 

 by the scanty numbers of food trees in that region, while the 

 annual campaign is profitable enough for those who participate 

 to insure' a careful scrutiny of every shrub in that entire district. 

 The suggestion might be made that a substantial bounty paid 

 for each female moth when she first appears might result in mate- 

 rially lessening the possibility of numerous larvae later, but one 

 must remember that the moths are not as easily found as the 

 cocoons. 



A NOTE ON THE MUSCULAR COAT OF THE VENTRICULUS OF 

 THE HONEY BEE (APIS MELLIFICA). 



BY G. F. WHITE, 



Bureau of Entomology. 



While studying the pathology of Nosema-disease a fact of 

 some anatomical interest in connection with the muscular coat 

 of the ventriculus (stomach) of the adult honey bee was observed. 

 Nosema-disease is an infectious disease among adult honey bees 

 (Apis mellifica) caused by a protozoan parasite, Nosem.a apis. 

 Entomologists generally are familiar with pebrine, an infectious 

 disease among silkworms (Bombyx mori) caused by a protozoan 

 parasite (Nosema bombycis} of the same genus. 



In pebrine all of the organs of the insect, whether it be the 

 larva, the pupa, or the imago, are invaded by the parasite. An 

 examination of the tissues show that the hypodermis, tracheal 

 epithelium and muscle fibers are usually very heavily invaded 

 while the fat cells, the epithelium of the stomach and the cells 

 of the reproductive system are also invaded although to a some- 

 what less extent as a rule. In Nosema-disease on the other hand 

 only the adult bees are susceptible to infection and only the 

 ventriculus and the Malpighian tubules are invaded by the 

 parasite. The epithelium (fig. 1) of the stomach of the in- 

 fected bee invariably contains the parasite while rarely are the 

 cells of the Malpighian tubules invaded. This distribution of 

 the germ in the Nosema-infected bees encouraged a somewhat 

 careful study of the histology of the stomach. 



The epithelium of the organ was found to be as it is generally 

 described. Variations due to the age of the bee and the func- 

 tional activity of the cells at the time the tissues are fixed are 

 observed. Nosema apis gains entrance to the bee by way of the 



