222 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



President Arthur Gibson: The next paper by Messrs. Crawford 

 and Spencer is one of a series. 



THE EUROPEAN CORN BORER (Pyrausta nuhilalis Hubn.) : 

 LIFE HISTORY IN ONTARIO i 



By H. G. Crawford, Entomological Branch, Ottawa, and G. J. Spencer, Ontario 

 Agricultural College, Giielph, Out. 



The apology for presenting so incomplete a study rests upon the fact 

 that this is a recently introduced and already widely distributed insect, 

 spreading with great rapidity, and capable of doing very serious damage. 

 Consequently its reaction to Canadian conditions where it has demon- 

 strated its ability to increase over 300 per cent in a single year and where 

 its presence results in severe damage to our com crop, cannot but be 

 of interest and value. 



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

 or stubble, either standing or lying on the ground. Almost any other 

 not absolutely submerged shelter, from com leaf on the groiind 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 larvae do a variable 

 amount of boring and possibly feeding in preparing the pupal chambers 

 from which an outlet for the escape of the adult is made. 



Pupation in the field in 1921 began on May 30th, being practically 

 complete by June 22d, though one or two larvae 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 de- 

 layed, pupation did not begin until June 6th, ten days later. The 

 males began to pupate 7 days before the females, outntimbering them 

 until just before the end of the pupation period. Similarty with the 

 moths, the males began to emerge about 4 days before the females 

 and exceeded them in number until just before the end of the emergence 

 period, which extended from Jime 29th to August 12th. The dtu-a- 

 tion 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. 



^A joint progress report of the life history studies carried on at the laboratories 

 of the Dominion and Ontario Departments of Agriculture in the season of 1921, 

 at Port Stanley, Ontario, Canada. 



