40 BULLETIN 847, U. S. DEPARTMENT OF AGRICULTURE. 



Iii depositing her eggs the female beetle makes a slit in the bark 

 with her mandibles and then inserts her ovipositor and places the 

 egg between the bark and wood or between layers of the bark. About 

 9 or 10 minutes are required for the deposition of a single egg. Usu- 

 ally from 2 to 5 eggs are laid at a time. Probably all eggs are de- 

 posited by day, and the female in ovipositing shows a slight prefer- 

 ence for the sunny or exposed side of the trunk, 65 per cent of tho 

 eggs being found in one case on the exposed side of the tree. In the 

 latitude of West Virginia, the average number of eggs deposited by 

 a single female is apparently from 20 to 30. Oviposition in a given 

 locality extends over a period of from 50 to 60 days. 



The larvae begin to feed immediately after hatching and usually 

 grow rapidly the first season. Feeding is continued until cold 

 weather and is resumed again in the spring shortly before the blos- 

 soming time of the apple. The larva may spend from one to four 

 years in the tree, this stage being of longer duration in the North 

 than in the South. At French Creek, TV Va., 85 per cent of the 

 larvae remained in the trees two years before pupation, and 12 per 

 cent three years. At Winthrop, Me., 25 per cent remained in the 

 tree three years and 75 per cent four years. 



The pupal stage lasts about 20 days and the period is about coinci- 

 dent with the blossoming time of apple. After changing to beetles 

 the insects remain in the pupal chamber for from 5 to 10 days and 

 then gnaw a circular hole through the bark at the upper end of the 

 chamber and escape. The beetles appear in the South earlier than in 

 the North. Between Demorest, Ga., and Munising. Mich., there was 

 a difference of 75 days in the dates of the emergence of the first 

 beetles. At French Creek, W. Va.. beetles issued from the wood 

 during two different years over a period of 30 days. Other years the 

 period was shorter. May 12 was the earliest date for the appear- 

 ance of a beetle in any year at French Creek, and June 23 was the 

 latest date. A few beetles lived 60 days after issuing. 



Pairing may take place at once or may be delayed 10 days after 

 emergence. Eggs are laid soon after pairing. In an apple orchard 

 containing 310 King, 311 Grimes, and 311 York Imperial trees, the 

 Grimes were most severely attacked in four out of five years, nearly 

 50 per cent of all the eggs being laid in Grimes trees. This could 

 be accounted for in no other way than that the borers showed a 

 preference for this variety. 



Experiments showed that the female beetles during oviposition 

 are capable of flying to a considerable distance, but that they prefer 

 to place their eggs in trees near the place where they themselves have 

 developed. By preventing the development of adults in the orchard 

 trees and in other trees growing within from 300 to 600 feet of the 

 orchard, subsequent infestation was reduced 73.6 per cent. 



