26 GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 



others, it needs some qualification. Some of the causes given for this value 

 from the plow are that this tuj-ns the eg-gs up and exposes them to the weather, 

 by which is usually understood to the effects of "freeze and thaw." It is, how- 

 ever, extremely doubtful if this freeze and thaw have any bad effects upon the 

 eggs. In the first place they are deposited so near the surface as to be always 

 subjected to these alternations, even if left untouched. In a climate like that 

 of Minnesota where the soil is frozen for long periods to a depth of several fee^ 

 the result of displacing grasshopper eggs from a depth of less than two inches 

 to the surface certainly cannot subject them to very different conditions from 

 normal. Apparently the real good resulting from cultivation lies in the break- 

 ing up of the egg masses and thus exposing the eggs not to freeze and thaw 

 but to the effects of bleaching and drying in part, and in rendering them 

 more easily carried away by stich natural forces, as running water, etc., than 

 when protected by the earth blanket in which they were placed. With this 

 thought in mind, the harrow suggests itself as an agent of equal importance 

 to the plow. It has been argued that the plow "upends" the egg mass and that 

 the young hatching are unable to penetrate the "capsule" and so perish. With- 

 out regard to the experiments upon which this idea was based, we must here 

 take note of the fact that in natural conditions the "capsule" having been sub- 

 jected to the varied agencies of the weather, has become, by the time of hatch- 

 ing, a soft jelly-like consistency that certainly could offer little resistance to a 

 young grasshopper. Another theory has been that by deep plowing late in the 

 fall the eggs are turned under to a depth so great that the young hoppers must 

 perish before reaching the surface. While thei'e may be something in this 

 theory, it is evident that conditions must vary widely with the nature of the 

 soil and with the amount of subsequent moisture, etc. Under some conditions 

 the soil may not be sufficiently compact to offer any serious obstacle to the 

 young hopper. Furthermore, we have been informed by observers that after 

 trying this plan and plowing even as deep as seven inches, they have observed 

 young hoppers emerging from the ground the next season, the only apparent 

 result being that hatching was delayed somewhat. Taken all in all we niust 

 confess that at the present time we feel that the real value in cultural work 

 against grasshoppers lies in breaking up the egg mass, and hence the plow, 

 unless followed by the harrow, is of less real value than we have thought. Cer- 

 tain practical reasons which need not be here discussed tend to prevent late fall 

 plowing but it is evident that even though early plowing is necessary and cus- 

 tomary late harrowing may yet act to good advantage both as to the eggs and 

 as to the soil itself. Spring plowing to be of value must be done just at the 

 time when the eggs are hatching and to be of most value should be followed 

 .by the harrow. In fact the harrow should be used in spring on all lands that 

 were plowed in the fall and should be used at the time when the young are 

 just emerging from the eggs. 



The plan of burning off large tracts to kill young locusts has been tried 

 in many places with somewhat varying reports. In any case there is more or 

 less danger of damage to the hay crop when the burning is applied late enough 

 to be of any real benefit. Often there is also danger of losing control of the fire 

 itself unless great care is taken. From the fact that grasshoppers are not so 

 abundant in raw prairie as appears to be generally thought the burning over of 

 wild hay land is not usually of much real value. In burning off the reverted 

 areas and stubble where the greatest numbers of the young hopopers are to be 

 found, it is fi-equently best to scatter straw over the area and burn this. * * 



While the necessity for action early in the season has already been men- 

 tioned in connection with various methods of control, it is a matter of such 

 prime importance that it may be treated again even though it may be in part 

 a repetition. Among the reasons for this early action we may note first the 

 fact that then the young hoppers are wingless and can travel only by hopping. 

 They are thus more easily caught. Another fact is that at first they are 

 much more gregarious and tend to cluster together in masses, while later in the 

 season they scatter widely and any method of killing must be less effective than 

 before. The nature of the vegetation offers another reason for early action, 

 since then the plants, whether weed or crop, are low and do not interfere with 

 control methods. For instance in early May it is easy to use a hopperdozer 



