178 P). C. Enti)M(ilogical Society 



3 mm. in len<;'tli, they feed to some extent and undergo at least one moult 

 before they emerge to continue their development. Signs of activity in 

 the spring are evidenced by the production of fresh frass and by an 

 enlargement of the gallery. These larvae may become 5.5 mm. in length 

 before they emerge, although the average length is not more than 3 mm. 

 in the spring. 



There is a certain natural mortality of the larvae during winter. 

 An exact record taken in nnsprayed orchards in April, 1919, at Penticton, 

 following the winter of 1918, showed that 31.5% of the larvae had died; 

 66.4% out of the 125 galleries examined in April, 1919, contained live 

 larvae, while S.l'/f contained dipterous larval parasites. 



Si'KiNCi Larval Habits 



The over-wintering larvae, in the early spring, leave their burrows 

 and move to the buds and blossoms. This migration commenced in 1918, 

 on April 10th, at the time when the apricot and peach blossom buds were 

 well swollen, and on April 21st. 1919, when apricots were nearly in full 

 bloom and peaches were in the "pink." This migration, once started, 

 was rapid. It was at its height on April 16th, in 1918, and on April 27tli, 

 in 1919; in the former year when apricots were in full bloom and in the 

 latter year when the apricot petals were commencing to fall and peaches 

 were in full bloom. Larvae were actually found infesting the buds of 

 peaches on April 16th, in 1918, and on April 25th, in 1919. There is, 

 however, as has already been pointed out, certain larval activity within 

 the burrows previous to emergence. In 1919 this activity was apparent 

 in the presence of fresh frass at the entrance of the burrows on April 9th, 

 fully two weeks before any migration took place from the burrows. A 

 period of cold, backward weather in the spring of 1919 checked the 

 development which might have followed rajiidly after the first appear- 

 ance of activity. 



Following the migration of the larvae from their over-wintering 

 burrows, m\ich feeding takes place at various points on the tree; buds 

 and twig growth are fed on and mined, blossoms and young fruit* are 

 bored into and destroyed. At first there seems to be an inclination for 

 the larvae to move freely over the tree, feeding here and there before 

 settling in one fruit or twig. This is an im])ortant jioint which has its 

 bearing on the value of arsenical sprays. This larval activity of the first 

 generation continued until the middle of June, at which time practically 

 all had pujiated. In 1918, full grown larvae, measuring 12-15 mm. in 

 length were found preparing to pupate on May lOth ; in 1919 the first 

 pupae were found on May 28tli, though they commenced their prepara- 

 tion on May 23rd. 



From these habits it may be seen that twig, leaf and fruit develop- 

 ment are all attacked by the larvae in the spring and that there is a 

 certain movement of the larvae over the tree, although they seldom move 

 off the original twig on which they passed the winter. On the records 



