221 



full and interesting, and is appended. The variation in life history 

 referred to above consists in the fact that the insect hibernates as an 

 adult, and lays its eggs in May and June. Most other injurious spe- 

 cies, it will be remembered, lay their eggs in the autumn, and these 

 eggs hibernate. Late fall and winter plowing, therefore, usually aftbrds 

 a good remedy in the case of other species. With the American locust 

 other means have to be adopted, and these are found in the use of 

 hopper-dozers while tlie insects are yet unfledged, and in the use of the 

 bran-arsenic mash for both unfledged and winged individuals. Exi)eri- 

 ments tried by Mr. Coquillett, and which are detailed in his report, 

 show that the poisoned mash seems very attractive to this species, and 

 indicate that by its use at the proper time much damage may be pre- 

 dented. 



The cause of this extraordinary local abundance of the insect is difii- 

 cult to ascertain. Mr. Coquillett is inclined to follow the popular local 

 opinion in attributing it to a successful hibernation on account of the 

 mildness of the winter of 1893-'94. As a general rule, however, we 



Fig. 20.— Schistocerca americana : a, first stage; 6, second stage; f, third stage— enlarged twice 



(original). 



believe that mild winters, particularly when followed by late and severe 

 spring frosts, as was the casein the spring of 1894, are not so favorable 

 to successful hibernation as uniformly severe winters, and we are 

 inclined to think that we must look further for the cause of this out- 

 break. Last year extensive forest fires in the region about Roanoke 

 may have had some influence. The comparative drought of the present 

 summer may have been favorable to the development of the insect in 

 greater numbers than usual. Other and unknown causes, appearing 

 to produce a smaller number of natural enemies than customary, may 

 also have been immediate factors. Such speculations, however, are of 

 little practical account, and the important fact is that the insect was 

 present in great numbers and may increase and spread another year. 

 Curiously enough, although the species is everywhere common 

 throughout the South, its early stages have not been figured, and, so 



