Nov. s, 1921 Pale Western Cutworm 295 



at Wilsall. Hundreds of eggs were laid in the breeding cans during the 

 last week in August and the first week in September, but with the ex- 

 ception of three larvae which hatched August 30 no eggs hatched unless 

 they were placed in a very humid atmosphere. The larvae mature 

 within the eggs in from 10 to 20 days and may remain for months in this 

 condition, waiting merely for proper moisture conditions to allow them 

 to break through the eggshell. Examples of this may be of interest. 

 Moth number 1427-G laid 160 eggs on August 24 and 25. These were 

 placed on a piece of filter paper in a Mason jar. They were allowed to 

 stand in the laboratory for 10 days and were then placed in an incubator 

 and held at day temperature of 80° F. and night temperature of 60°. 

 At the end of three weeks practically all the eggs had darkened, and the 

 black heads of the young cutworms could be seen through the eggshells, 

 but none had hatched. On October 4 a few drops of water were added 

 to the filter paper, and when the jar was opened 24 hours later 70 larvae 

 were found to have hatched. On October 1 1 water was again added to 

 this jar, and 40 more larvae hatched out. 



On October 27 a few drops of water were added to another jar of 62 

 eggs which were laid August 29. In two hours 8 larvae had hatched, 

 but no more hatched during the next six hours. Twenty-four hours 

 later all of the eggs had hatched. On October 27 moisture was added to 

 eggs that had been kept in the greenhouse since August 30, and in two 

 hours many of them had hatched. On this same date one of these eggs 

 was placed on a block of plaster of Paris, and water was slowly dropped 

 upon it from a medicine dropper. At the second drop the larva began 

 to move within the egg. Soon it began to move its mandibles and after 

 several attempts the eggshell was punctured, and within 30 minutes 

 after the first drop of water was added the larva was free from the shell 

 and actively moving about. On November 20 eggs that were laid 

 August 30 and had been kept for a month in a small tin can on a shelf 

 directly over a radiator were examined, and living larvae were removed 

 from them by carefully breaking the eggshells with fine needles. 



On November i twenty eggs which were laid on August 29 and had 

 been kept indoors were placed in two small wooden boxes and buried in 

 a pail of damp sand. The pail was set on the ground, outdoors, where 

 it was covered with snow practically all winter. The eggs were exam- 

 ined once a month, but none hatched until the second week in April 

 when all the eggs were found to have hatched and the larvae were alive 

 and vigorous. 



From our studies of the egg it would appear that if there is sufficient 

 moisture and proper temperature condition the majority of the eggs 

 will hatch in the fall, while if it is unusually dry or cold weather starts 

 early the eggs will not hatch until the following spring. Strickland {18) 

 found eggs on frozen ground December 3, which would indicate that in 

 Canada some of the eggs at least do not hatch until spring. 



