432 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



From this table we see that the eggs laid at Manhattan, Kans., in 

 the fall of 1876, and obtained by Mr. Eiley for his experiments early in 

 Kovember, may have already received as much as 1140 = 600 + 540 hours 

 of a hatching temperature, or about 47 complete days, more or less, de- 

 pending on their exposure, which was allowed for in framing the work- 

 ing hypothesis given in the preceding section. 



By adding up the numbers in the initial column of the table just given, 

 and comparing with our standard, 1,440 hours of temperature 60°, we 

 find that the times at which the hatching would begin are about as fol- 

 lows : 



Eggs deposited Septeniber 1, 1875. 





At- 



Will have received— 



And begin to hatch- 



Lati- 

 tude. 



Fort Garry .. 



1,264 hours of hatching temperature by June 30 

 1,41) hours of hatching temperature by June 30 

 1,407 hours of hatching temperature by May 31 ' . 

 1,434 hours of hatching temperature by April 30 

 1,404 hours of hatching temperature by Nov. 30.. 

 1,320 hours of hatching temperature by Oct. 31 . . 



Early in July, 187C 



o 

 50' 



Ereckenridge . . 

 Yantton 



do 



46.5 



Early in June, 18T6 



42 5 



Ncrtli Platte 



Early in May, 1876 



41.5 



Dodge City 



Corsicana 



During December, 1875% 



During November, 1875 



37.5 

 32 



This table shows the rapid development of the eggs in the region 

 south of Kansas, where their hatching may, under favorable circum- 

 stances, begin in December, though those born then will be killed by 

 the cold that would not have injured their eggs. For Minnesota, Ne- 

 braska, and Kansas our table agrees well with the hatching times of the 

 majority of the insects as reported in Eiley 's Locust Plague, page 97. For 

 Manitoba our data are rather later than that given by Eiley, but would 

 correspond to the region north of Dakota and Montana. In general, 

 however, it is apparent that a revision of these figures in the light of 

 careful observations to be made in the future will confirm the general 

 accuracy of the present method of computing and predicting the times 

 of hatching, and will give data for much more accurate calculations. 



CHAPTER XVL 



EFFECTS THAT GENEEALLY FOLLOW SEYEEE LOCUST 



INJUEY. 



There are some interesting consequences that usually follow severe 

 locust injury, and that are well worth recording. Not to dwell on the 

 immunity which, as we have seen (pp. 247-8), the farmer is likely to en- 

 joy the year following severe injury from the young insects, there is 

 invariably, throughout the Temporary Eegion, a marked 



CONTRAST BETWEEN SUMMER AND AUTUMN. 



^'After the insects have left, or by the end of July in the latitude of 

 Saint Louis— earlier or later as we go south or north— the ravaged 



