THE ORTIIOPTERA OF MINNESOTA. 19 



stincLive tendency to push upwards is also remarkable. In 

 glass tubes, in which eggs were hatched in order to 

 watch the young, these last would always turn their heads 

 and push towards the bottom whenever the tubes were 

 turned mouth downwards; while in tin boxes, where the 

 eggs were placed at different depths in the ground, the 

 young never descend, even when they w^ere unable to ascend 

 on account of the compactness of the soil above. 



The above minute account of the manner in whicheggs are 

 laid, and how the young are enabled to reach the surface, 

 plainly indicates one good method by which the hatching of 

 the eggs may either be prevented entireh-, or by which the 

 young may be prevented from reaching the surface. By 

 plowang the fields containing eggs of the Rocky Mountain 

 locust, we perform two operations: first of all we remove 

 the eggs from near the surface and cover them with five or 

 six inches of soil; secondly, vveinvert the position of the hole 

 containing the egg-mass, so that instead of its mouth point- 

 ing upwards, it now points downwards. At all events, the 

 young insects are prevented from reaching the surface, if 

 this becomes compacted by rain and snow. Consequently if 

 we plow during autumn or soon after the eggs are laid we 

 are safe ; although if we plow in the spring with a normal 

 amount of rain, we also effectually prevent their hatching. 

 Plowing has this additional advantage: the egg-masses 

 in many cases are thorottghly broken up, the individual 

 eggs become surrounded by earth and moisture, and being 

 no longer protected by the water-proof coat of dried mucous 

 matter, they soon rot and perish. 



To repeat again : If we desire to get rid of the migratory 

 species of locusts now infesting several places in the state it 

 is absolutely necessary to plow every inch of the cultivated 

 ground throughout the invaded region or all land in which 

 eggs have been laid. 



The Lesser Migratory Locust lays its eggs in essentially 

 the same manner. It always prefers, however, old stubble 



