88 



When the pupal cells have been broken up the distance which the 

 emerging moths can work their wa}^ through the soil depends almost 

 entirely on the consistency of the latter. Very loose, friable, sandy 

 soil seems to offer no obstacle at all, as the following experiment will 

 show. Two lots of nine pupte were placed in separate jars, buried 

 beneath 2 and 4 inches, respective!}^, of dr}^ finely broken sandy 

 loam. In each jar seven perfect and one imperfect moth emerged. If 

 the earth is damp and packed down upon the pupae, either by rains or 

 otherwise, the result is very different. One box centaining sixteen 

 pupae covered with 1^ inches of soil and thorough!}^ wetted was allowed 

 to dry hard. Only two perfect moths emerged, the three others which 

 emerged failing to expand their wings. The others were found 

 embedded in the soil in their split pupa cases, from which they had 

 been unable to escape. Other scattered observations show that from 

 2i to 5 inches of moderateh^ moist, heavy earth will almost entirely 

 prevent the emergence of perfect moths. 



The effect of submergence under water was also tried upon pupre in 

 cells and loose in the black soil of the sort occurring in the river bot- 

 toms that are subject to yearly overflow. In each case the earth was 

 covered to a depth of 1^ inches with rain water. At normal summer 

 temperatures the pup^e could not withstand twentj^-four hours' sub- 

 mergence, but in the ice box, at a temperature of from 50° to 60° F., 

 they were unharmed b}^ from four to six days'' submergence. 



MORTALITY DURING THE PUPAL STAGE. 



Under normal conditions mortality during the pupal stage is but 

 slight, although a number of larvfe die in their underground cells before 

 pupating. In a lot of forty larvae entering the soil during the latter 

 part of July, onl}'^ twenty-four, or 60 per cent, emerged, while of larvae 

 which successfull}^ pupate from 80 to 90 per cent usually emerge. 

 The mortalit}^ among the hibernating pupae under normal conditions 

 must be veiy much greater. In one case twenty-five larvae nearh^ or 

 quite full grown were placed in a box with food on October 30, 1903, 

 and the box sunk level with the soil, at Hetty, Tex. No moths having 

 emerged by June 2, 1904, the pupae were exhumed and only two live 

 ones found, one of which later failed to emerge. Traces of five others 

 were found. Of a second lot, five larvae entering the soil at Victoria, 

 Tex. , November 5, 1903, not a single one survived the winter. In a 

 third lot at Calvert, Tex., consisting of seven pupae buried in loose 

 earth, November 3, 1903, but two survived the winter, while of twenty- 

 five larvae left to pupate at the same time, ten had pupated and sur- 

 vived. The results shown all point to a much greater mortality for 

 this generation, although much seems to depend on local conditions. 



