MICROBIOLOiSY OF DISEASES OF INSECTS 643 



Zonocercus elegans, the so-called "elegant grasshopper" of South 

 Africa, a non-migratory species, was used in inoculation experiments 

 with this bacillus. It was concluded that this disease at best could 

 be employed only as a supplementary measure in dealing with the inva- 

 sion of these insects under conditions that prevail in South Africa. 



The Philippine locust, Pachytylus migratoroides, has given negative 

 results with B. acridiormn. (Mackie). 



II. Ants. — A species of small ant near Paris was annihilated in 

 191 1 by B. acridiorum. 



Selenopsis gemminata, near Buenos Aires was annihilated in 1912. 

 Several drops of the culture were placed in each ant hill. 



Atta sexdens, a veritable plague in the tropical and sub-tropical 

 countries was annihilated at Chaco and Tucuman after the virulence 

 had been increased for this species of ant by many passages. 



III. Caterpillars. — A field of cotton which was being ravaged by 

 caterpillars was treated with B. acridiorum. Four days afterward all 

 the caterpillars were dead while a neighboring field, treated simul- 

 taneously with Paris green, still contained many living caterpillars. 



B. acridiorum does not attack the silk-worm, Bombycis mori; it kills 

 the cockchafer, Melolontha vulgaris, by injection but not by ingestion. 



Birds and mammals in general are immune to this bacillus. 

 One notable exception is the sewer rat which dies from generalized 

 septicemia a few hours after injection. The rat was immune to cul- 

 tures ingested. 



Bacillary Septicemia of the Caterpillars of Arctia caja L. 

 Bacillus caja — Picard and Blanc* 



History and Distribution. — In 1913 the vineyards of central 

 France were almost completely destroyed by two diseases; one of these 

 was a fungus disease caused by Empusa aulica, the other was a septi- 

 cemia of bacillary origin. 



Symptoms. — The caterpillars become flaccid and emit a nauseating 

 odor; their digestive tube contains only a clear liquid free from all 

 organisms. The blood contains a pure culture of a bacillus with which 

 the disease has been produced artificially. 



* Picard, F. and Blanc, G. R. On a bacillary septicemia of caterpillars of Arctia caja L. 

 Compt. rend. acad. soi. 156, 1913. PP- I334-I336. 



