926 MICROBIAL DISEASES OF INSECTS 



CAUSAL ORGANISM. B. melolontha resembles B. acridiorum of d'Herelle with the 

 exception of the following characteristics: the bacillus is longer, and in agar culture 

 produces a green fluorescence in five to six days. It is distinguished from the bacillus 

 of d'Herelle in addition by its pathogenic action on the silk- worm, Bombyx mori. 



METHODS OF INFECTION. Injected into the general cavity, B. 

 melolonthce kills the cockchafer in twelve to thirty-six hours, and where 

 its virulence has been augmented by several passages through this 

 insect, always in less than twenty-four hours, but per os, it is as 

 inactive as B. acridiorum. Seventy-five per cent of healthy cock- 

 chafers show the presence of B. melolonthce in their digestive tube, 

 sometimes in massive culture. This is always the case with cock- 

 chafers affected with septicemia. 



This blood disease seems to be of intestinal origin however, as with 

 the locust. B. melolonthce,' a common parasite of the intestine of the 

 cockchafer passes into the general cavity only under special conditions 

 yet unknown. When this organism is removed from the intestine and 

 injected into the general cavity, septicemia is produced. 



It is as virulent for the silk-worm by injection as for the cockchafer, 

 and as inactive by ingestion. 



EUROPEAN FOUL BROOD 

 Bacillus pluton White* 



HISTORY AND DISTRIBUTION. This type of foul brood, sometimes 

 known as "black brood," or "New York bee disease" is not nearly as 

 wide spread in the United States as is American foul brood, but in cer- 

 tain parts of the country it has caused enormous losses. It is spread 

 over England, Germany, Switzerland and other parts of Europe and 

 has been noted many times during the last decade. 



SYMPTOMS. The presence of disease can usually be detected in an 

 experimental colony during the week that feeding is begun. The first 

 indication of it may be that only a portion of a larva is seen in a cell, 

 the remaining portion having been removed by the bees. Aside from 

 an observation of this kind, the earliest indication one gets from the 

 macroscopic examination is that sick larvae are found among the un- 

 capped brood. 



Sick larvae manifest certain symptoms during the course of the 

 disease by which its presence can be diagnosed while the larvae are still 



* White G. P.: European foul brood. Bui. 810. B. of Ent. U. S. Dept. of Agr. 1920. 



