EFFECTS OF fl!8wiN^UNTH^!GBs^^^ 357 



~Experhncnt 31. — From ten egg-masses, placed 2 iuches beneath the surface, the 

 young commenced issuing from the sides, as in the preceding experiment, January 31. 

 None issued directly through the surface of the soil, and none issued after the border 

 was pressed more iirmly'to the tin. Subsequent examination showed the soil pene- 

 trated in devious directions, but none of the insects had reached higher than within 

 three-qnarters of an inch of the surface. 



Experiment 32. — Ten egg-masses placed 3 inches below the surface. The young 

 began, January 31, to issue from the sides, as in Experiments 30, 31. Upon pressing 

 the ground more firmly around the borders, none afterward issued, and subsequent 

 examination showed that the young ha,d tunneled the earth in tortuous passages to- 

 ward the sides, and perished there, without reaching nearer than within an^inch of 

 the surface in the middle of the bos. 



Experiment 33. — Ten egg-masses placed 6 inches below the surface. On February 1 

 the young commenced to issue, as in the preceding experiments, from the side, and 

 continued to do so till the 4th, when the earth was pressed more closely to the tin. 

 None issued afterward. Subsequent examination showed that some had succeeded in 

 working their way upward through the soil to within 2 inches of the surface; but 

 most had reached the sides, and there collected and perished between the tin and the 

 Boil. 



Other experiments, made in glass tubes where the movements of the 

 insects could be watched, all produced results similar to those above 

 given ; and all point to the conclusion that where the newly-hatched in- 

 sect has not the natural channel of exit (previously described) which was 

 prepared by the mother, it must inevitably perish if the soil be moder- 

 ately compact, unless cracks, fissures, or other channels reaching to the 

 surface are at hand. 



" The actual experience as to deep plowing under of the eggs is some- 

 what conflicting, and in some light, dry soils a good number of them 

 will hatch late if turned under a foot ; yet, from our own observations, 

 and a vast amount of experience gathered together, we recommend it 

 as profitable. If delayed till spring, it should be done just as the young 

 begin to hatch, as it is then most effectual. The plowing will be 

 effectual according as the soil is porous or tenacious, and according as the 

 surface is afterivard compressed by liarroiving and rolling. From the 

 experiments already recorded, it is obvious that, all other things being 

 equal, a plowing of four to six inches will prove more effectual in spring, 

 if the ground be subsequently harrowed and rolled, than deeper plowing 

 with no subsequent comminution and compression." 



The experience prior to 1877 is on record in various publications ; but 

 that of 1877 was most valuable, because, in many instances, township 

 meetings were held the previous autumn to provide for combined action 

 in the plowing up of roadsides and other public places where eggs had 

 been laid. As may be seen by Mr. Whitman's report (App. 1), the good 

 effects of plowing the eggs under deeply was very marked in Minne- 

 sota, wherever the work was thoroughly done. Even when turned 

 under to a depth of five or six inches, the hatching, if it occurred at all, 

 was too late to cause any fear. " Eggs plowed under in corn-land were 

 found to be unhatched up to the 2 1st of June, but when brought to the 

 surface they hatched at once ; and, without any question, large numbers 

 of eggs turned under in heavy grounds never hatched at all. At any 

 rate, it ought to be learned from the present year, that with a good 

 growth of wheat, we have nothing to fear from locusts that come strug- 

 gling forth during the month of June." 



