PAPERS ON ZOOLOGY 305 



dad to combat the sugar-cane frog-hopper; Forbes 

 (1888), Snow (1889), and others have attempted to use 

 Spo rot rich um glohuliferum Speg. to control the chinch 

 bug; Eolfs (1907) and Fawcett (1908) have used 

 Sphaerostilhe coccophila Tul. and Ophionedra coccicola 

 E. and E. against the San Jose scale and the purple scale 

 on the orange; and the last two investigators have alsa 

 employed various other fungus diseases to combat the 

 white fly in the citrus groves of Florida. 



Very diverse opinions have been expressed by investi- 

 gators who have worked upon this problem, concerning 

 the success of their experiments and the promise of this 

 method of insect control for practical work, Krassil- 

 schik claimed to have produced an epidemic of ''green 

 muscardine-' among the weevils in the beet fields at 

 Smelk, which destroyed from 50 to 80 per cent of these 

 pests. Eorer reports the destruction of as many as 93 

 per cent of the sugar-cane frog-hopper in his field ex- 

 periments in Trinidad, and most promising results have 

 also been reported from work with the fungTis diseases 

 of scale insects and of the white fly in Florida. On the 

 other hand, however, some workers have reported the 

 comjDlete failure of their experiments, and have ex- 

 pressed grave doubts concerning the practical utility of 

 the method. Between these extremes, all degrees of suc- 

 cess and failure have been reported, and all degrees of 

 optimism and pessimism expressed by investigators who 

 have studied the problem. On the whole, perhaps, a 

 summation of these various reports and opinions tends 

 rather to discredit than to recommend the method. 



In spite of the disrepute into which the insecticidal 

 use of fungus diseases has fallen in many quarters, the 

 startling destructiveness of occasional natural epidemics 

 of these diseases remains, and their importance as a 

 constantly present natural check upon insect oscillations 

 caimot be denied. These facts, therefore, together with 

 the franlv differences of opinion expressed by students 

 of the subject, have seemed to justify reopening the 

 question, and have led to the organization of a series of 

 studies of which the present paper is a partial report. 



