464 



THE MONTHLY BULLETIN. 



lo leave the ease entirely, and live for a time as true leaf miners. The actual move- 

 ments of feeding are easily observed by holding the leaf up to the light. As soon as 



the larva has become accustomed to han- 

 dling it will proceed to feed. Annoyance 

 of any sort is likely to cause it to retreat 

 into its case. 



In the study of the life history of this 

 insect the nearly adult larva; were collected 

 and placed in paper-bag breeding cages. 

 The bags were tied over apple twigs to 

 retain the insects with a supply of natural 

 food. In addition to the paper-bag colonies 

 some collections were reared on green 

 apples in the laboratory. 



In 1910 the first adults were obtained 

 on May 23. The moths lived three to 

 five weeks in the paper-bag cages and the 

 first eggs were observed on July 5. Evi- 

 dently egg laying had been in progress for 

 some time, as about half were hatched. 

 The eggs continued hatching until July 13. 

 These eggs are not readily seen without a 

 hand lens, and are so obscurely placed on 

 the under sides of the leaves among the 

 plant hairs that the failure to see them 

 immediately is explained. The unhatched 

 eggs are light yellowish green, nearly 

 hemispherical and decidedly fluted. The 

 flat surface is tightly pressed against the 

 leaf surface. 



On hatching the young larvae bore 

 directly into the leaf through the bottom 

 of the egg. For at least one and possibly 

 two instars the young caterpillars remain 

 within the leaf as true leaf miners. How- 

 ever this may be, small larvae in cases were 

 first observed on August 13. 



These young larvae continue to feed 

 during the summer and fall, but do not 

 become more than one-fourth grown before 

 the beginning of the hibernating period. 

 These lai-vae were found hibernating on 

 the twigs and bud scales as early as 



Fig. 139. Characteristic leaf 

 mines of ft volckei. (Original.) 



November 3. After this date the number of hiber- 

 nating specimens increased very rapidly and appar- 

 ently very few of the insects fell with the foliage. 

 The hibernation is, of course, conducted within the 

 case which is securely attached to the twig by silk. 



The period of hibernation continued until the 

 blossoms were opening in the following spring. 

 There appears to be two spring molts, and the 

 larvae grow rapidly until pupation which extends 

 from the middle of May to the middle of June. 

 Pupation takes place in the case of the mature 

 larva and the moth emerges from the rear portion 

 of this case. 



The feeding larvas are seldom found except 

 attached to the under side of the leaves while the 

 pupae are moct frequently attached to the upper 

 surfaces. Pupae are also found attached to twigs 

 and fruit. It is the more mature or spring form of 

 the larva? which are likely to injure the fruit. The 

 extent of the injury to the fruit appears to depend 

 on the relative abundance of the larvae which largely 

 by accident leave the foliage and attack the fruit. 



Fig. 140. Larvae of the 

 apple leaf-mining case-bearer 

 greatly enlarged. (Original.) 



