160 EOLAND THAXTER ON THE 



Hyphantria textor in a jelly tumbler, and fastened above them a grasshopper from which 

 the spores were being rapidly discharged. These larvae were then fed for eight days in 

 a closed jelly tumbler, at the end of which time the Spilosoma had died, and, soon after 

 being placed in a moist chamber, produced a luxuriant growth of conidiophores. In the 

 meantime all of the Hyphantria larvae had died from insect parasites, with the excep- 

 tion of two which spun cocoons after a few days. I was entirely unable to transfer the 

 disease from caterpillars to grasshoppers; but I was quite as unsuccessful in infecting 

 grasshoppers from grasshoppers. The reinfection of. caterpillars I found more easy, 

 although about two-thirds of the caterpillars used for this purpose showed no signs of 

 the disease and pupated as usual. I was unable to repeat the expeiiment of cross infec- 

 tion wdth any satisfactory result, owing to the fact that it was impossible to obtain cat- 

 erpillars in any number, or good material of 7i^. Orylli with which to infect them : I was 

 obliged therefore, in a second experiment, to use larvae of Pyrrharctia isabella which 

 were in the hibernating condition. Of five larvae used, one died in eight days and con- 

 tained resting spores; while the rest were not affected after several weeks. I do not 

 consider these experiments as in the smallest degree conclusive in themselves; but a 

 comparison of other species shows that the hosts of Empusae may be widely different 

 in the same species, and therefore a specific distinction, which, as in the present instance, 

 would rest entirely on the character of the host, should not be considered of any value, 

 even if my experiments did not show that the hosts may be, to a certain extent, inter- 

 changeable. 



I have been much surprised at the difficulty encountered in communicating the disease 

 among similar hosts, although in the case of grasshoppers this may be perhaps accounted 

 for from the fact that I used only imagines, which may afibrd a less ready entrance to 

 the genninating spores than younger stages of these insects. In the case of the hairy 

 caterpillars, however, I see no reason why infection should not have been successful in 

 every case. A specimen of Ceuthophilus, found at Kittery, which was discharging spores 

 in great quantities, was also used in an attempt to infect three individuals of the same spe- 

 cies which were confined with it in a small tin box. The living crickets were put into 

 the box late in the afternoon when the spore discharge was at its height, so that several 

 hundred spores at least must have come in contact with each specimen. On the follow- 

 ing morning the living crickets were not only well powdered with spores, but had eateii 

 about half of the infected specimen. jSTevertheless, alter having been kept for more 

 than two weeks, they showed no signs of the disease. In view of these facts, it is not 

 surprising that my success in cross infection should have been so incomplete, and it may 

 reasonably be assumed that so radical a change of hosts is probably a somewhat gradual 

 process even in nature, the fungus, as has been already noted, requiring one or more 

 generations to become firmly established under its new conditions of nutrition. 



Since the species is so widely distributed and generally abundant, there seems to me 

 no good reason for believing that the resting spores described as E. Calopteni and 

 found in Caloptenus at Ames, Iowa, belong to a different species ; and I have therefore 

 placed this as a synonym. Through the kindness of Professor Fallow, I have been ena- 

 bled to examine authentic specimens of JS. Calopteni collected by Professor Bessey which 

 difier in no respect from the usual resting spores of JSJ. Grylli. Professor Farlow has also 



