PAPERS ON ZOOLOGY 303 



sively in adipose tissue. The infected nymphs could 

 easily be distinguished from the healthy ones by their 

 opaque appearance. They however did not seem to suf- 

 fer from the infection. Further details still are needed 

 to complete the observations. 



The MicrosiDoridian nature of the latter two forms can 

 not be doubted, because the writer could determine every 

 characteristic of Microsporidian spores in both of them; 

 i. e., the characteristic appearance of spores and the pres- 

 ence of a polar filament in the spore which can be made 

 to extrude under suitable treatment. 



SUMMARY 



Myxosporidia are common parasites among fish in the 

 vicinity of Urbana, 111. The infection is heav^' in many 

 cases. The effect of the parasites on the host body is 

 in some cases fatal. 



Microsporidia seem to be also common among some 

 aquatic insects in the same locality. The larvae of Culex 

 pipiens appear to receive mortal influence by its para- 

 sites, Theloliania magna Kudo. 



SOME LBIITIXG FACTORS IX THE USE OF FUN- 

 GUS DISEASES FOR COMBATING INSECT 

 PESTS* 



E. D. Glasgow and C. S. Spooxee, Natural History 

 Survey, Ureaxa 



Insects are attacked in nature by many fungus diseases. 

 Sporadic cases of such diseases are common, and may 

 be found by a diligent collector at almost any time. Oc- 

 casionally, however, some of these diseases appear in 

 epidemic form so as almost to exterminate locally, insect 

 species which pre^'iously had been abundant. 



That house flies are commonly decimated in autumn 

 by a fungus disease of that insect, Empusa muscae, is 

 weU known. Even the most superficial observer can 



* From the Entomological Laboratories of the Illinois State Natural 

 History Survey, S. A. Forbes, Director. 



