930 MICROBIAL DISEASES OF INSECTS 



SYMPTOMS. No external symptoms are noted. Lesions are pro- 

 duced in the epithelium, the cells undergoing degeneration, perhaps 

 shortening the life of the lug- worm. Bad. arenicola seems to be con- 

 fined chiefly to the ciliated tracts, as was determined by microscopical 

 examination of sections. 



METHODS OF INFECTION. No methods of infection are noted. 

 From the type of the disease, however, infection per os is suggested. 



CAUSAL ORGANISM. Bacterium arenicolcs averages about n/i long and IM 

 broad. Extreme individuals measure 7/4 to i7/x long by 0.7/1 to 1.3;* broad; some of 

 the larger forms are slightly sinuous in outline; no flagella; chromatophile granules 

 determined by staining with iron-hematoxylin, are present, often in considerable 

 numbers, scattered through the cell; these granules are often concentrated into 

 transverse bars both of which in some specimens are refractile. The cytoplasm 

 stains with difficulty with plasma stains. Division is transverse. One terminal 

 spore is formed which does not cause the enlargement of the rod to any extent. 

 No cultural characteristics are given. 



IMPORTANCE. This^disease is of no special economic importance. 



PSEUDOGRASSERIE OF THE GlPSY-MOTH CATERPILLAR 



Bacillus lymantricola adiposus Paillot 



HISTORY AND DISTRIBUTION. In August, 1917, Pa illot( France) 

 noted a gipsy moth caterpillar which presented exterior symptoms of 

 both grasserie and flacherie. It was infected by two coccobacilli to 

 which he gave the names Bacillus lymantricola adiposus and Bacillus 

 lymantricz j3. The former bacillus was the sole cause of the disease in 

 question as was proved by experimentation. The following season 

 was so dry that epizootics were rare among insects and no new cases 

 were observed. 



SYMPTOMS. A few hours after inoculation with B. lymantricola 

 adiposus the blood of the caterpillar possessed the same milky appear- 

 ance as that of caterpillars affected with grasserie. This is due, not to 

 polyhedral bodies as in true grasserie, but to the presence of fat glo- 

 bules in the blood. The name pseudograsserie is given to this disease 

 as it resembles grasserie as to external symptoms only. 



CAUSAL ORGANISM. B. lymantricola adiposus is a coccobacillus i/j. in diameter and 

 2/j. long; strains well, showing bi-polar staining. In the blood of the caterpillars 

 of Lymantria dispar, this organism shows most unexpected forms; e.g., giant forms, 

 made up of a more or less round mass whose diameter may be 7 to 8/u, and greatly 



