MICROBIOLOGY OF DISEASES OF INSECTS 65 1 



plied in pulling the mass from the intestine frequently causes the typ- 

 ical transparent, mucus-like substance surrounding the central mass to 

 stretch and the enclosed whitish substance to break into segments; 

 this appearance is very characteristic. 



If the disease is more advanced, a portion of the intestinal content 

 may flow out in the form of a sac, the wall of which is very easily bro- 

 ken. When broken the content of this sac-like structure will flow out 

 as a rather thin whitish or yellowish white fluid containing small whitish 

 granules that vary in size. If the disease is far advanced and the larva 

 probably dead, the enveloping substance of the intestinal content is 

 so easily broken that often only the whitish or yellowish-white fluid 

 flows from the ruptured wall of the larva. 



Dying larvae diseased with European foul brood frequently show 

 the segments of the body marked off less distinctly than living healthy 

 larvae. 



Causal Organism. — B. pluton, the organism of European foul brood, is a small, 

 non-spore forming organism, sharply pointed at one or both ends, ab6ut in long and 

 less than 0.5/1 in breadth, on the average; occurs frequently in pairs; single individuals 

 vary very markedly in size and shape. 



This organism has never been cultivated, but sections of larvae in various stages 

 of the disease show B. pluton to be the first invader of healthy larvse. B. pluton is 

 easily killed between 60° and 65° in ten minutes. 



Methods of Infection and Control. — These are essentially the 

 same as those for American foulbrood. 



Bacterial Septicemia of Larv^ of the Lamellicorn^ 



Bacillus sepHcus insectorum — Krassilstschik 



History and Distribution. — This disease occurred separately 

 and together with graphitosis previously described. 



Symptoms. — The septicemia produced in larvae of the Lamelli- 

 cornae by B. septicus insectorum is characterized by a uniform browning 

 of the body of the larvae. As death approaches, the larva shrivels up 

 and when dead is about half its natural size and is of a deep brown color. 

 During the progress of the disease, the larva ejects a very black, abund- 

 ant, viscous, semifluid substance from the anus which soils the ex- 

 tremity of the abdomen. 



