15 



Cultivation. — Three methods were used to determine the efficacy of 

 the method of destroying eggs. Conditions were produced in breed- 

 ing cages as nearly as possible like those existing in the fields. Eggs 

 were collected in the fields a few weeks after cultivation had occurred, 

 and lastly careful observations were made in fields cultivated before 

 planting and those that were not. While none of these methods, taken 

 separately, would give exact experimental proof, yet when the results 

 of all three are considered, the estimate may be regarded as 

 approximate. 



Breeding cages showed that after egg areas had been broken, as 

 represented in fig. 3, and the eggs exposed to rain, frost, and sunshine 

 for two months, that over 80 per cent failed to hatch. We failed to 

 determine the influence of frost alone upon exposed eggs, but young 



Fig. 3.— Grasshopper eggs exposed by cultivation (drawings from a photograph). 



grasshoppers which had been hatched artifically, when subjected, 

 March 15, 1900, to a temperature of 32° F., all died. 



Of several hundred eggs collected on February 15 from fields which 

 had been plowed in December, 1899, and the eggs kept from further 

 exposure, only 30 per cent hatched and most of these came from egg- 

 pods which happened not to be thoroughly broken. 



From field observations where favorable contrast could be made in 

 egg areas cultivated and those left undisturbed the evidence in favor 

 of cultivating is,' to say the least, very conclusive. Mr. G. G. James, 

 of Mound Landing, Miss., states, in a letter dated March 14, 1900: 

 "While dragging a plow along a wagon road on March 12, the point 

 dug up a few clusters of grasshopper eggs, and after finding these I 

 had the entire road plowed up, and to nry astonishment I found quan- 

 tities of eggs its entire length. In a certain part, a space of about 20 



