20 BULLETIN 847, TJ. S. DEPARTMENT OF AGRICULTURE. 



DISTANCE OF FLIGHT OF FEMALE BEETLES DURING OPPOSITION. 



The probability that the female beetle during her egg-laying ac- 

 tivities does not normally wander far in search of host trees has been 

 suggested by the fact that the trees containing the larvae are usually 

 found in somewhat restricted groups. This grouping of the borers 

 occurs not only in orchards but in the woods as well, and indicates 

 that where host trees grow near together the adult females during 

 oviposition are not inclined to fly far from the trees in which they 

 develop. In an effort to obtain data bearing on this point several 

 experiments were carried out in West -Virginia, which are described 

 below. 



THE DABNAIX OBCHAED. 



This orchard contained 537 apple trees ranging in age from 4 to 

 about 20 years. In the summer of 1914 it was found to be badly in- 

 fested with rotindheaded apple-tree borers, and the trees were gone 

 over carefully after the eggs of the current season had hatched, all 

 the borers being removed and counted. The trees contained 141 

 borers, 106 of which had only recently hatched. The orchard was 

 surrounded by pasture lands and woods in which grew an abundance 

 of seedling apple, wild crab apple, hawthorn, and service trees. 

 Within a strip 600 feet in width surrounding the orchard these out- 

 lying trees were also examined and all the borers removed and 

 counted, the number of borers found being 95. This operation was 

 repeated annually for a period of 4 years, it being obvious that if 

 borers were not allowed to breed within the area all the young borers 

 found within the orchard after the first year would necessarily have 

 hatched from eggs deposited by female beetles which had flown into 

 the orchard from outside the 600-foot strip. 



In the second year of the experiment (1915) an examination of 

 the orchard trees showed that female beetles had crossed the 600- 

 foot strip and deposited 56 eggs. The third year (1916) only 1 egg 

 was deposited in the orchard. The fourth year (1917) beetles flew 

 across the boundary strip and deposited 44 eggs in the orchard trees. 

 While this was a. considerable reduction from the number of eggs 

 deposited annually in the orchard before the experiment began, still 

 it showed a rather general tendency on the part of the female beetles 

 to fly at least 600 feet in searching for trees in which to oviposit. 



In figure 2 are given plats of the Darnall orchard showing the 

 location of infested trees and the number of borers found at each of 

 the four annual examinations. 



