The Codling-Moth 115 



believe, the case as far west as Toronto. In the fruit growing districts 

 of West Ontario there are two broods, the second brood being invari- 

 ably the most destructive." 



From the above evidence we conclude that there is one well-defined 

 brood and usually a more or less complete second brood of the codling- 

 moth yearly in the New P'.ngland States, New York, most of New 

 Jersey, and part of Canada. Two well-defined annual broods occur 

 in Michigan, Illinois, Iowa, Missouri, Kansas, Nebraska, Western 

 Ontario, and Colorado, with sometimes a partial third brood in some 

 localities and seasons. In California, Oregon, New Mexico, and in 

 the South there seems to be three broods annually. We should have 

 more definite observations on this point in many states. It is not pos- 

 sible to define these dififerent regions by parallels of latitude, for the 

 variations in the number of broods depends upon differences in climate, 

 temperature, and latitude.* 



Whenever the first brood of worms transforms into moths the same 

 season, this usually occurs late in July and during August, and the 

 second brood of worms work from August on, many of them even 

 completing their growth after the fruit is stored. In those parts of 

 Europe where the insect is single-brooded, the moths do not appear 

 from the winter cocoons until the middle of June and in July. The 

 second brood is usually more destructive than the first, as it is more 

 numerous and works in the later and more valuable varieties of fruit. 

 In some years the partial second brood which works in New York 

 spoils many more apples than the first brood. 



This question of the number of broods of this pest is of great prac- 

 tical importance in connection with the methods of combating it. We 

 have learned how quite successfully to control it where there is one and 

 a partial second brood, or even two broods annually, but where there 

 are more than two broods we are not so successful. 



* Mr. Marlatt suggests (Proc. But, Soc. of Wash., III., p. 228) that " Dr. 

 Merriam's map showing the distribution of the total quantity of heat during 

 the season of growth and reproductive activity, presents an interesting agree- 

 ment in its zones with the available records in regard to the number of broods 

 of this insect. " '^ "" At least, a good basis is furnished for future obser- 

 vations." He thinks that the data thus far submitted indicates one annual 

 brood in Dr. Merriam's transitional zone ; two annual broods may be expected 

 in the upper austral life-zone, and three annual broods in the lower austral 

 zone. 



