1922 ENTOMOLOGICAL SOCIETY. 23 



The larvae of the European corn borer normally winter in corn stalks or 

 stubble, either standing or lying on the ground. Almost any other not absolutely 

 submerged shelter, from a corn leaf in the ground to the centre of the cob in the 

 crib, will serve for successful wintering. In the spring as soon as the weather 

 warms up, the larva? do a variable amount of boring and possibly feeding in pre- 

 paring the pupal chambers from which an outlet for the escape of the adult is 

 made. 



Pupation in the field in 1921 began on May 27th being practically complete by 

 June 22nd, though one or two larva? were taken in the following week. Adults 

 began to emerge June 16th, and by July 4th 90 per cent, of the moths had issued, 

 the balance following more slowly ; a small percentage failed to develop. 



In the laboratory where the whole process of development was delayed, pupa- 

 tion did not begin until June 6th, ten days later. The males began to pupate 7 

 days before the females, outnumbering them until just before the end of the pupa- 

 tion period. Similarly with the moths the males began to emerge about 4 days be- 

 fore the females, and exceeded them in number until just before the end of the 

 emergence period, which extended from June 29th to August 12th. The duration 

 of. the pupation period of the males varied from 8 to 18 days, an average of 12.33 

 days, while for the females it was distinctly less, from 7 to 17 days, an average of 

 11.29. At the laboratory located a little further inland the average durations, 

 however, were 12 days for males and 10.19 for females, a distinctly more rapid 

 rate. 



The male moths lived in confinement for from 6 to 21 days, averaging 13 

 days, while the females lived for from 10 to 31 days, averaging 17.4 days, with a 

 pre-oviposition period (20 females) of from 3 to 9 days, averaging 4 days. After 

 this period they laid from 95 to 988 eggs per female, at the rate of from 12-23L 

 an average of 75.3 eggs per day, in masses containing from 1-64 eggs, an average 

 of 33 per mass. All of the eggs kept under observation hatched. The duration of 

 this stage was from 3 to 8 days, averaging for the period between June 28th and 

 August 2nd 4.71 days. 



In the field a study of the incidence of egg laying on corn planted on May 

 31st in a field adjacent to the northern margin of an old corn patch of 1920, at 

 this time in oats and barley, was started. The moths began to emerge on June 

 18th from the old stubble in the standing grain, and eggs were not found until 

 July 1st when 5 masses were secured from 100 plants, though a most careful 

 search was maintained in the intervening period of 14 days; on July 3rd 15 masses- 

 were secured on approximately 200 plants, at which time egg laying was be- 

 coming general, and some masses were observed to be hatching. The corn at 

 this time was from 9-20 inches high. No eggs were laid until the corn averaged 

 about 15 inches in height. In the interval the adults were, without doubt, flying 

 southwest to another field planted on May 18th which, at this time, was markedly 

 in advance of the field under observation in development and finallv suffered a 

 loss of 65^. The field under study in the north,- however, was but 63.2% infested 

 and the loss would not exceed 5%. 



The first eggs taken in the season, however, were found in the field June 

 21st, and by July 15th hatching was general, and the infestation was shown up 

 very clearly on the unrolling leaves where the newly hatched larva? were feeding 

 at the base. The evidence of attack became clearly marked in the first week in 

 July, and by the second week the tassels were falling on the early planted flint 



