(^From the American Naturalist, August and September, 1880.) 



DESTRUCTION OF OBNOXIOUS INSECTS BY MEANS 

 OF FUNGOID GROWTHS. 



BY PROF. A. N. PRENJISS. 



ENTOMOLOGISTS have been for a long time endeavoring 

 to discover some available means for checking the ravages of 

 obnoxious insects, and of late the possibility of employing fun- 

 goid growths for this purpose has been receiving considerable 

 attention. The most important paper which has appeared upon 

 the subject is a pamphlet by Dr. H. A. Hagen, of Harvard Uni- 

 versity, in which he advocates the use of the Yeast Fungus for 

 the purpose in question. " Destruction of Obnoxious Insects, 

 Phylloxera, Potato Beetle, Cotton-worm, Colorado Grasshopper 

 and Greenhouse pests, by application of the Yeast Fungus." 

 Cambridge, 1879. A proposition of this kind, emanating from 

 so high an a-uthority, is worthy of the most careful consideration. 

 It seems that the possibility of destroying insects by infesting 

 them with fungi from spores artificially sown, attracted the atten- 

 tion of Dr. Bail, of Prussia, more than a dozen years ago. His 

 experiments, however, were not conducted with reference to the 

 point in question, but for the purpose of establishing the identity 

 of certain forms of fungi which had been regarded as distinct. 

 That Dr. Bail's conclusions do not follow from his experiments, 

 for instance, that the house-fly fungus (Empiisa muscce) and the 

 yeast fungus ( Saccharoniyces cerevisa) are merely different devel- 

 opments of the same species — is an opinion, I think, that every 

 mycologyst who has had experience in the growth of microscopic 

 fungi will endorse. This, however, does not affect Dr. Hagen's 

 main proposition, inasmuch as the identity of the fungus is of 

 small importance so long as it proves fatal to insects and its appli- 

 cation is practicable. Propositions of a similar nature to that of 

 Dr. Hagen's have been mad^ by other scientists, notably by M. 

 Pasteur some years since, whose investigations upon the silk- 

 worm disease led him to suggest to the French Commission du 

 Phylloxera, the possibility of destroying the insect which had 



