MICROBIOLOGY OF DISEASES OF INSECTS 633 



insects caused by a fungus disease is after a comparatively short time 

 entirely wiped out and another disease takes its place; in many places 

 bacterial diseases seem to have almost entirely supplanted the fungus 

 diseases. This succession of diseases among insects takes place with 

 such periodicity that those who are most intimately connected with 

 their study, can predict very closely both the duration of the epizootic 

 in progress and the time intervening before the onset of the next one. 

 This same periodicity takes place more or less among the more highly 

 organized animals but the "explosive" character is greatly modified 

 by the length of the life cycle. 



Miscellaneous Insect Diseases 



Bacillus erausquinii n. sp. was isolated from locusts of the species 

 Romalea miles in Argentina by Cullen and Maggio. It is said to have 

 many characteristics which distinguish it from B. acridiorum. 



A disease of the caterpillars of Gortyna.ochracea, and artichoke pest, 

 is recorded in the Department of Var, France. Bacillus gortynee was 

 isolated as the causal factor. 



Bacillus pyrameis I and II were isolated from the blood and tissues 

 of the caterpillars of Pyrameis cardui, another artichoke pest. These 

 may be distinct or merely varieties of a single species; they may repre- 

 sent one or more saprophytic species widespread in nature which are 

 readily adaptable to a parasitic life (Paillot). 



Two associated microorganisms, one a motile rod and the other a 

 coccus were the cause of epizootics destroying nearly all of the cater- 

 pillars of Gaileria melonella, the bee moth, which were being raised for - 

 experimental purposes (Metalnikov) . The rod form was the more viru- 

 lent on injection. The manner in which infection takes place was not 

 determined. 



Saprolegniace^e and Entomophthorace^.* — Some of the Sapro- 

 legnia (all water fungi) form conspicuous masses of mycelium around 

 dead insects in stagnant water. The Entomophthoracece are parasites 

 of insects on land. One of these, Empusa musca, destroys the common 

 house-fly, which, after death from this disease, is found attached by its 

 mouth parts to windows or woodwork. 



• Prepared by Charles Thorn. 



