THE EUROPEAN CORN BORER AND ITS CONTROL. 41 



Table XIII. — Life Cycle Swrnnary of Second Generation. 



I Excluding winter period of inactivity. 



SEASONAL HISTORY AND DEVELOPMENT. 

 Number of Generations. 



There are two annual generations of the European corn borer in Massa- 

 chusetts, a generation here being considered to begin with the egg and 

 terminate with the moth of the same generation. 



Eggs of the first generation are deposited during late May or early 

 June, and the resulting larvae pupate about the middle of July. The 

 moths emerge during late July and early August to deposit eggs of the 

 second generation. 



These eggs are deposited, therefore, during late July or early August, 

 and the resulting larvae feed on, or within, their food plant until the advent 

 of severe winter weather. Feeding is resumed with the coming of warm 

 weather in the spring, and the larvae pupate about the middle of May. 

 The second generation moths emerge during late May or early June, and 

 deposit eggs for the first generation. 



A few moths of the second generation have emerged in life-history 

 cages during September and October (see Table IX), but these indi- 

 \'iduals died without depositing eggs. Under exceptional circumstances 

 it is possible that moths emerging at this time may deposit eggs for a third 

 generation, but this has not yet been observed. 



Seasonal History. 



The European corn borer passed the winter of 1917-18 as nearly full- 

 grown larvae of the second generation within their tunnels in various food 

 plants. 



The first pupa of the second generation was found in the field May 6, 

 and the majority of the overwintering larvae pupated between May 15 

 and 20. 



The first moth of the second generation was observed in the field on 

 May 16. Moths began to emerge from indoor cages May 18, and maxi- 

 mum emergence occurred during the period from June 1 to 4. The last 

 emergence of second generation moths was recorded on July 9, from labo- 

 ratory cages (see Table XV). 



