54 



be exceedingly tenacious of life, since several years may elapse between 

 outbreaks of the disease. Still no such regular intervals of recurrence 

 of the disease have been noted as would tend to show a periodicity. 

 Neither does there seem to be a regular time of the year for its appear- 

 ance, nor has it a preference for insects of any particular age, since 

 those of all ages seem at one time or another to succumb to its attacks. 

 Sometimes, though rarely, it may be noticed first in late spring or 

 early summer; at others, and more frequently, during midsummer, 

 and again even in late summer and early autumn, or possibly not until 

 just before cold weather commences in late fall, when it seems to be 

 most common. 



Dr. Thaxter says: ''The artificial propagation of Empusre by the 

 infection of fresh hosts I have found a much more difficult matter 

 than one would suppose, even where the infected host was of the same 

 species as that from which the spores were obtained for this purpose." 

 (L. c. , p. 152.) Not alone has Dr. Thaxter found this difficulty in secur- 

 ing artificial infection, but other persons have also learned the same 

 fact fully when attempting to make use of the fungus as a means of 

 destroying locusts. In truth, the writer has found it impossible to 

 impart the fungus artificially to a single insect in either the laboratory 

 or the field. It might be well, however, to state here that these exper- 

 iments by the writer were purposely carried on in a very crude man- 

 ner, since their object was to secure results that might also be obtained 

 b} T farmers who are not equipped with carefully arranged laboratories. 



If we make an exception of the matter on this subject that has been 

 reported from the Bacteriological Institute of Grahamstown, Cape of 

 Good Hope, it appears that up to the present time all of the experi- 

 ments that have been attempted for the purpose of growing this fungus 

 artificially in the laboratory have been very unsatisfactory. After hav- 

 ing studied the subject carefully by reference to the available literature, 

 and noting critically such facts as appear pertinent, and which are 

 given below, it is the writer's opinion that the exception just suggested 

 is justifiable. 



The typical region for Empusa grylMis Europe, and in that country 

 perhaps it has been most frequently reported. But the reader should 

 not infer from this statement that this fungus is of rare occurrence 

 elsewhere, for such is not the case. Here in North America it is among 

 the most abundant of fungus plants, and it is to be regularly met with 

 each 3 T ear in suitable localities throughout the length and breadth of 

 the land. In fact, it very frequently occurs as an epidemic among the 

 locusts in regions where various species of these insects have developed 

 as pests. This same or a closely allied fungus was occasionally 

 referred to by correspondents as indigenous to Argentina while the 

 writer was in that country several j^ears ago, and quite recently 

 notices of its occurrence in Japan and the Philippine Islands have 

 been seen. 



