PROCEEDINGS, 1918 17 



As will be seen from the table the date of first emergence 

 was July 14. This agrees approximately with previous years 

 observations, viz. that the fly first appears about the middle 

 of July and reaches its maximum a few days later. In our 

 experiments previous to 1917, we found that the first emergence 

 in our cages was later than that observed in the orchard. This 

 was doubtless due to the fact that, in order to remove the pupae 

 from the soil and to divide them into lots of one hundred pre- 

 vious to placing them in the cages, we have followed the prac- 

 tise of immersing them in cold, water. The pupae float on the 

 water and can thus be readily counted out, but the cold bathing 

 has the effect of retarding their emergence from one to two 

 weeks. By performing this work in the fcll or early in the 

 spring instead of shortly before the natural time of emergence, 

 this effect is eliminated and the difference does not appear. 



It is evident that whatever the difference in the early 

 spring — whether the season is early or late — the time of emer- 

 gence of the apple maggot is approximately the same. It is a 

 matter of common observation that the appearance of insects 

 that commence their activities early in spring, coincident with 

 the starting of growth of the plants upon which they feed, var- 

 ies considerably with the season. This is not apparently true 

 in the case of the apple maggot, a fact which obviously has an 

 important bearing on the control of the pest. 



Emergence According to Variety of Apple. 



The figures shown in Table No. 1 were taken from maggots 

 derived from several varieties of fruit, viz. Yellow Transpar- 

 ent, Astrakhan, Bough Sweet, Gravenstein and a natural hard 

 apple resembling a russet. Table No. 2 shows the emergence 

 of adults according to the variety of fruit from which they 

 were derived. 



