EOUXDHEADED APPLE-TEEE BOEEE. 



25 



fields in which scattering seedling apple and service trees grew. 

 Undoubtedly beetles developed within these outstanding trees and 

 flew into the experiment orchard to oviposit, providing thereby for 

 an unknown number of borers, which can not be eliminated from 

 the numerical results of the experiment described below. The rather 

 heavy infestation, shown below, of rows 1 to 5 can be accounted for 

 only on the ground of an overflow of adult females from the ad- 

 jacent older orchard. 



In the experiment orchard during three separate years newly 

 emerged beetles of both sexes were distributed among the trees of 

 row 16, which extended through the center of the orchard. The 

 beetles used were removed from rearing cages and placed on the 

 trunks of the trees, care being exercised to disturb or excite them as 

 little as possible. The sexes of the beetles were about equally di- 

 vided as to numbers. After a sufficient time had elapsed for all the 

 eggs to hatch which were deposited by the liberated females, the 

 orchard was gone over and the number of borers found in each row 

 recorded. The results showed with some degree of accuracy the ex- 

 tent to which the females in ovipositing wandered away from the 

 trees upon which they were liberated. In 1914, 25 females were 

 liberated on row 16; in 1916, 87 females were liberated on the same 

 row; and in 1917, 12 were distributed in like manner. In the year 

 1915, nine females were liberated on row 29. In all cases males ac- 

 companied the females. 



Table IX shows the distribution by rows of the borers found in the 

 orchard each season following the liberation of the female beetles 

 on row 16. 



Table IX. — Distribution of rottndheaded apple-tree borers hatching principally 

 from eggs deposited by female beetles liberated on the central row of the 

 orchard. Orchard contained 31 rows of 32 trees each and beetles were placed 

 on row 10. 





Number borers found. 







Number borers found. 





No. of 





Total. 



No. of 

 row. 







Total. 



row. 

















1914 



1916 



1917 







1914 



1916 



1917 





1 



1 



20 



25 



46 



17 



18 



23 



28 



69 



2 



3 



23 



13 



39 



18 



7 



25 



19 



51 



3 



5 



23 



23 



51 



19 



9 



14 



21 



44 



4 



2 



23 



23 



47 



20 



5 



29 



21 



55 



5 



1 



22 



2 



25 



21 



7 



19 



24 



50 



6 



2 



14 



9 



25 



22 



12 



13 



22 



47 



7 



9 



21 



4 



34 



23 



10 



12 



12 



34 



8 



3 



28 



7 



38 



24 



9 



14 



23 



46 



9 



22 



24 



7 



53 



25 



9 



11 



18 



38 



10 



9 



21 



7 



37 



26 



8 



14 



3 



25 



11 



3 



12 



8 



23 



27 



3 



26 



8 



37 



12 



14 



19 



19 



52 



28 



7 



21 



6 



34 



13 



12 



31 



9 



52 



29 



1 



18 



18 



37 



14 



10 



10 



18 



38 



30 



6 



12 



14 



32 



15 



7 



30 



26 



63 



31 



1 



31 



18 



50 



16 



24 



29 



50 



103 













Total number borers 1, 375 



