57 



nothing will do so. Even had the insects which were collected and 

 buried been killed by poison, boiling water, heat, or in some other 

 violent manner, and treated in a similar wa}^, the result would in all 

 probabilit}" have been quite similar. But when these insects die from 

 disease and drop to the ground in a variety of localities, and later are 

 gathered together, there is no telling how many different kinds of 

 saprophytic fungi may have come in contact with and adhered to them. 

 Even Empusa-killed insects, attached to vegetation a considerable dis- 

 tance from the ground, would themselves become infested, and under 

 favorable conditions support a great variety of these molds. 



In our experiments with the fungus mentioned in this paper as 

 Mitcor vacemosus we have found that such locusts as have been dipped 

 or sprinkled with sugar-water cultures of it are killed; but when 

 turned loose in the field there is no apparent spreading of the fungus 

 to other 'hoppers. Neither did we have any success in destroying 

 them when the inoculation was attempted by feeding the fungus to the 

 insects along with bread crumbs, etc., that had been used for culture 

 media. It is surmised that by thus dipping the insects into the liquid 

 containing the fungus some of the mycelial threads and spores of 

 the latter enter the stomata, as well as the sutures between the rings 

 of the abdomen and thorax, and start to grow, and in a short time use 

 up the fluids and vital tissues of the body suflBciently to cause death. 



Since none of the other fungous diseases of locusts, aside from that 

 caused by Empusa gryUi^ seem to have received much attention 

 heretofore, it has been thought best to devote some space to their dis- 

 cussion here. Especially does this seem w^arranted because of the 

 numerous references made to them in these pages. 



SPOROTRICHUM Sp. 



The first of these other locust-attacking fungi that deserves mention 

 was discovered b}^ the writer in 1897 while investigating the destruc- 

 tive locust problem of Argentina, South America. In the month of 

 June, when the insect then under investigation was hibernating, or, 

 more correctly speaking, resting, and confined chiefly to the more 

 northern districts of that country, it was thought best to occupy the 

 time in gathering data of various sorts. It was on one of the field 

 excursions which were regularly made at intervals, as this work was 

 progressing, that dead fungus-covered nymphs of the destructive 

 locust were discovered securely tucked away in dense bunches of a 

 species of grass common to a large portion of the open country. 

 These dead saltonas (as the nymphs of these insects are called in that 

 countr}^) had evidently been destroyed by the fungus in large numbers 

 during the previous year. Still, so securely were they tucked away 

 in these clumps of grass that fulh' eight months later they not only 

 remained nearly perfect in form, but also retained their colors suffi- 

 ciently to make their identity certain. 



