42 



times as much damage as the lirst generation, and it is necessary to 

 know whether a second generation is present in order that the proper 

 measures of control ma}' be emplo}" ed. Great biological interest also 

 attaches to this problem, as it affords an excellent opportunity for the 

 study of the effects of different climates on one insect. 



The term ''generation" is used instead of "brood" because it 

 describes more definitely the idea intended. A generation in this con- 

 nection means a number of individuals which pass through certain 

 stages at about the same time, having begun in the same stage at the 

 beginning of any given season. A succeeding generation is the aggre- 

 gate of all the different broods of the individuals of the generation 

 immediatel}' preceding. A new generation is considered to begin with 

 the egg stage, and continues through all the transformations of the 

 insect until the moth dies. Many authors object to the term "partial 

 generation," ])ut as there is a condition in which this term can be used 

 with a definite meaning, it ma}' be well to use it. For instance, in 

 some sections of the country all the insects pass through one genera- 

 tion; a few, becoming more advanced than others, may succeed in 

 passing through the pupal and moth stages and la}' eggs, from which 

 larvfe hatch and enter the fruit, whereas the majority of the insects 

 hibernate as larva:> and do not transform until the following spring. 

 As those insects which enter the fruit in the fall do not for the most 

 part complete their development, at least in the field, they are termed 

 a partial generation. 



In taT)ulating the results of o])servations in regard to the time of the 

 various stages we find that at certain periods more individuals of a 

 generation are in certain stages than at other times; and likewise we 

 find periods when there are fewer insects of a certain stage than at 

 other times. These periods are designated respectively the maxima 

 and minima of the different generations. It is always considered that 

 the larva% pupte, and moths found in the early spring belong to the 

 last generation of the preceding season and may be termed the hiber- 

 nating generation. 



From the writings of Furopean authors we find that there is but 

 one generation of the codling moth in northern Furope, including 

 Fngland (Westwood) and northern and central Germany, while the 

 evidence of Reaumur and Schmitberger shows that at Vienna and in 

 France there are two generations. American writers have at various 

 times recorded many observations of variations in the number of 

 generations in the United States. Fitch seems to indicate the pres- 

 ence of but one generation, while Harris says a few may transform and 

 enter the fruit in the fall, though the majority of the first generation 

 hibernate. Fletcher reports that careful observations extending over 

 ten years convince him that near Ottawa, Canada, there is l)ut one 

 regular generation of the insect, while in the fruit-growing districts 



