THE AMERICAN ENTOMOLOGIST. 



269 



seem more healthy than before. I think if 

 potash was mixed with salt and water it 

 would be an improvement, and am going 

 to use it that way. You have my best 

 wishes for the success of your book on 

 orange insects, which will supply a want or 

 need long felt by intelligent orange-grow- 

 ers." 



• — ^ 



THE USB OF FUNGUS GROWTHS TO DESTROY 

 INSECTS. 



In the " American Naturalist " for Au- 

 gust and September of the present year 

 Prof. A. N. Prentiss of Cornell University, 

 has an interesting contribution to the 

 above-named subject. After reviewing 

 the observations made by previous writers 

 Prof. Prentiss makes the following remarks 

 on the normal presence of fungus spores : 



" In examining the question as proposed 

 by Dr. Hagen, many facts must be taken 

 into account before deciding upon the pro- 

 bable results. It must be remembered 

 that the air is at all times charged with 

 the spores of fungi. Dr. Cunningham 

 found that ' spores and other vegetable 

 cells are constantly present in atmospheric 

 dust, and usually occur in considerable 

 numbers ; the majority of them are living 

 and capable of growth and development.' "* 



" Dr. S. M. Babcock, who is determining 

 the chemical changes of cheese during the 

 curing process, finds it impossible to avoid 

 mold in the curd except by heat and 

 anesthetics (ether and chloroform). He 

 states that the spores seem to be in the very 

 milk used in the experiments. 



" In the Botanical Laboratory, where 

 molds and yeast are cultivated at certain 

 times for experimentation, the air soon be- 

 comes charged with spores. 



" Growing in the same laboratory and 

 rooms directly connected with it, are plants 

 which require constant care lest they be 

 overrun with their several insect pests. No 

 disease appears to have attacked these in- 

 sects. It may be that they do not feed upon 

 the yeast, and for this reason escape. It is 

 not necessary that the spores be eaten by 



* " Microscopical E,\aminations of Air," from the " Ninth 

 Annual Report of the Sanitary- Commissioner,*' Calcutta, 187d. 



the insect in the case of the fly fungus 

 {Empusa miiscm). Huxley says :* " It 

 has been ascertained that when one of the 

 spores falls on the body of a fly, it begins 

 to germinate and sends out a process which 

 bores its way through the fly's skin ; this 

 having reached the interior cavity of the 

 body, gives off the minute floating cor- 

 puscles which are the earliest stages of 

 Empusa. The disease is 'contagious,' be- 

 cause a healthy fly coming in contact with 

 a diseased one from which the spore-bear- 

 ing filaments protrude, is pretty sure to 

 carry off a spore or two. It is 'infectious,' 

 because the pores become scattered about 

 all sorts of matter in the neighborhood of 

 the slain flies." 



" In this connection it should be noted 

 that while the insects which infest more or 

 less the plants growing in the laboratory 

 have not been affected in any way by the 

 fungi or their spores, the plants themselves, 

 in some instances, have been seriously in- 

 jured. On one occasion, recently, some 

 experiments which had been commenced 

 with much care upon Diosera rotiindifolia 

 were brought to a sudden end by a mold 

 which completely overrun and destroyed 

 the plant. That the air of the laboratory 

 should become abundantly charged with 

 spores, would, of course, be expected from 

 the large number of experiments in the 

 growth and propagation of microscopic 

 fungi which at times are being conducted 

 by the members of the classes in mycol- 

 ogy. Indeed after a time the spores be- 

 come so abundant that all apparatus has to 

 become thoroughly cleansed and fumiga- 

 tion by sulphur resorted to in order that 

 the experiments with the fungi themselves 

 should not be defeated. 



" The abundance of these spores of many 

 kinds, including those of the house-fly 

 fungus, emphasizes the fact that Aphides 

 and other plant insects seem to thrive in 

 the midst of these spores without any 

 diminution of their vigor or power of re- 

 production." 



A series of nine experiments in apply- 

 ing the yeast fungus to Aphides, as con- 



* '* Lay Sermons, Addresses and Reviews," p. 372. 



