8 BULLETIN 113, U. S. DEPARTMENT OF AGRICULTURE. 



mine open and ejecting all excrement at the point of entrance. Thus, 

 if the larva, which can be seen through the epidermis, be disturbed, 

 it "will rapidly crawl to another part of the mine; and if followed, 

 will escape at the entrance hole. 



The larvse show no preference as to the point of entrance, eating 

 their way into the leaf tissues at any point from the midrib to the 

 edge. 



One or many mines may be constructed in a single leaf, according 

 to the degree of infestation. Where the insects are numerous, the 

 mines form a network covering the leaf. It is evident that the adult 

 female in depositing her eggs lays a number at one time on adjacent 

 leaves, as the mines usually appear in groups, several affected leaves 

 occurring on the same twig or neighboring twigs. 



Upon the arrival of the first cold days of fall the larvse begin 

 leaving the mines to construct the small silken hibernacula in which 

 they pass the winter. The desertion of the leaf mines commenced 

 about September 12 (1913), the temperature showing the first con- 

 siderable drop of the season at that time. By September 17 prac- 

 tically all the larvse had disappeared from the mines. However, 

 upon picking off small pieces of loosened bark, or lifting up old 

 bud scales, the larvse were discovered spinning the minute cocoons 

 which were to be their winter shelter. 



No preference was shown in the selection of a place for hiberna- 

 tion, the larvse taking possession of the first available protection. 

 On large trees they confine themselves to the twigs and smaller 

 branches, but on small trees they may be found in abundance on the 

 larger limbs and trunk. The hibernating larvse on large trees, even 

 where the infestation is severe, are difficult of location, being very 

 small and inconspicuous. However, after a few warm days in the 

 spring the larvse begin to appear in great numbers, as if spontane- 

 ously. 



As the weather warms and the buds on the fruit trees swell, one 

 may discover, upon close observation, minute masses of reddish or 

 greenish pellets upon the buds. This is the excrement which the 

 larva within has deposited at the entrance to its burrow (PL II, 

 figs. 3 and 4). 



The first larvse at Benton Harbor were observed working in the 

 buds in considerable numbers on April 15, when the buds were just 

 beginning to swell. They probably began emerging in small numbers 

 one or two days before. 



The insect appears to show little preference as to the point of its 

 attack on the bud, for it enters either at the side or at the tip. As a 

 rule those entering at the side do so just at the edge of the bud 

 scales, although sometimes one will pierce the scales themselves. In 



