THE ORTIIOPTERA OF MINNESOTA. 



21 



REMEDIES AGAINST LOCUSTS. 



As has been stated before, the only method to reduce and 

 destroy these injurious insects, that promises success, is the 

 plowing of all the land in which eggs have been deposited. 

 And in this case, as in so many others, where measures are 

 directed against destructive insects, concerted action is all- 

 important. If one farmer does this work in a careful man- 

 ner, and his neighbor refuses to plow up a piece of meadow 

 land filled with eggs, all the work of the one farmer will be 

 more or less performed in vain, as the other careless one 

 can breed upon his land enough locusts to destroy the crops 

 of many of the surrounding farms. We still lack laws that 

 in a case like this can force the negligent farmer to do his 

 part of the work to get rid of such dangerous intruders, and 

 ■unless such laws are made and enforced, no uniformly good 

 results can be expected from any methods that might be 

 applied to rout the enemy. 



Since the method employed to kill the locusts depends al- 

 most entirely upon the question: Can voung insects reach 

 the surface of plowed fields, or not? It was very important 

 to make some experiments to be able to give a positive re- 

 ply to that question. To do so eggs of locusts [spretus and 

 atlanis) were planted at different depths in flower pots 

 which contained soil similar to that from which the eggs 

 had been removed. The result of these experiments may be 

 learned from the table below. 



SOIL KEPT DRY. 



Eggs planted 1 inch below surface produced 93 per cent of locusts. 



2 inches 



3 



4 



5 



6 



86 

 51 

 13 

 02 

 none 



SOIL MOISTENED FROM TIME TO TIME. 



planted 1 inch below surface produced 87 per cent of locusts. 

 " 2 inches " '" ' 



3 " 



4 " 



6 



43 



11 



01 



none 



