540 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



supplied. In one cage containing cankers of the New York 

 apple ca.nker, Sphceropsis malorum, and spores of the blister 

 canker Nummularia discreta Tul. applied to foliage, an examina- 

 tion of fifty pellets showed twelve pellets without spores of either 

 fungus; twenty-eight pellets with spores of the New York apple 

 canker, and twenty pellets with spores of the blister canker. 

 In many instances spores of both diseases were found in the 

 same pellets. 



2. When crickets were starved two days before feeding, spores 

 of various fungi passed throiigh the intestinal tract in a period 

 of six and one-half hours. 



3. When tree crickets were allowed to feed normally before the 

 tests, spores of various fungi, including the New York apple 

 canker and blister canker, were found in the excreta four days 

 after diseased wood was removed from their diet. 



4. Cultural tests of spores in the excreta showed that spores 

 of the New York apple canker and the Mica Inky Cap (Coprinus 

 micacious) passed unharmed through the intestinal tracts of the 

 crickets. Spores of the blister canker showed poor germinating 

 qualities. The feeble growth of the stock cultures suggests that 

 the spores possessed low vitality, which may be explained by the 

 fact that they were taken from museum material nearly one 

 year old. The excreta of these insects possess a rather extensive 

 flora, which includes such forms as Penicillium, Alternaria, Pesta- 

 lozzia, Asperillus, a Myxomycete, and many bacteria and yeasts. 

 Most of these showed a high rate of germination after being 

 subjected to the digestive processes of the tree crickets. 



5. In twelve attempts to establish the New York apple canker, 

 the Coniothyrium canker and brown rot (Sclerotinia fructigena 

 (Pers.) Schroet.) in peaches and apples, all proved failures except in 

 one experiment where there were three slight infections by the 

 Coniothyrium canker. On account of the readiness with which 

 the insects feed on the spores and the abundance of these organ- 

 isms in the excreta, it would appear from the work already 

 accomplished that conclusive experimental proof of such carriage 

 of bark diseases ought not to be difficult to demonstrate, especially 

 with a better understanding of the conditions favoring inocula- 

 tion and incubation, to which plant pathologists are now de- 

 voting considerable attention. 



While the foregoing data dealing with the viability of spores of vari- 

 ous bark diseases after passage through tree crickets are new, it should 

 be stated in conclusion that the existence of pathogenic microorganisms 

 in the digestive tract of insects and their degrees of resistance to the 



