84 



of this disease should be a welcome one when we consider the vast amount 

 of injury caused by the white grubs and the difficulties attendant on the 

 control of these insects. According to Miss Northrup the disease is wide- 

 spread throughout several of the United States, occurs in Porto Rico 

 and probably in Europe. 



June Beetle and White Grub 



The symptoms of the disease is a blackening of the affected area 

 which assumes a shiny appearance. The legs are often attacked and may 

 fall off. In dry soils death does not always occur among the diseased 

 larvae, but the organism works rapidly in wet soils and death takes place 

 very quickly. Miss Northrup considers that this explains the fact that 

 the white grub injury is decidedly more marked during dry seasons. 



The causal organism is a micrococcus which in microspical prepara- 

 tions may be arranged singly or in groups. They are usually found either 

 in the cells of the integument or in those of the alimentary canal. 



The Micrococcus is usually accompanied by a gas producing bacillus 

 which Miss Northrup regards as being probably B. septicus insectorum 

 Krassilstchik. This causes a putrefactive decomposition of the larvae 

 which spreads rapidly. Insects affected with this organism show a brown 

 colouration as distinct from the shiny black of ilf. vigrojaciens. 



In January 1914, several months prior to the publication of Miss 

 Northrup's work. Dr. Harrison received a culture of M. nigrofaciens, and 

 photographs of diseased larvae and tissues from her. These he gave 

 to me suggesting that it would be of interest to discover whether the or- 

 ganism is pathogenic to the Lachnosterna larvae in this vicinity. Apart 

 from this I was interested in Miss Northrup's work, because I had pre- 

 viously noticed in dead white grubs a blackening of the integument re- 



