200 Journal of Agricultural Research voi. xxn.No.4 



Seasoned Hicoria. Experiment II*. — ^Attempts were made in 

 April, 191 7, to develop a colony adapted to seasoned wood by caging two 

 females and one male on wood cut in October and dry seasoned. Eggs 

 were laid and larvse entered the bark but developed very slowly, never 

 entering the wood. Only three lived to pupate, and these made their 

 pupal cells between the bark and wood. All three pupae died during 

 the winter. 



In May, 1918, the experiment was repeated with three females and 

 three males and wood cut in November, 191 7. In the fall of 19 18 a 

 number of larvse lived and pupated, but all were below normal size. 

 Only a few adults emerged in April, 191 9, and these were below normal 

 size. 



1 1^. — Dr. A. D. Hopkins, in 19 16, recorded a dying hickory tree heavily 

 infested by Cyllene picius with no evidence of primary injury from other 

 causes. 



This suggested that a strain capable of attacking living trees might 

 be produced, and attempts were made to secure a colony in such a tree. 

 A small hickory 3 inches in diameter was selected and entirely stripped 

 of leaves August 11, 1916. April 30, 191 7, it was again defoliated, and 

 80 adults were caged on it. The adults laid eggs and the young larvae 

 entered the bark, causing sap to flow from the wounds. However, all 

 died after growing to 3 mm. in length. 



In April, 19 18, the tree was again defoliated, and 156 adults were caged 

 on it. The same results were observed. 



During both years the tree put out healthy foliage after artificial defo- 

 liation, but it died in August, 19 17. In no case did the Cyllene larvae hve 

 to mine more than % inch beneath the bark. 



QuERCUs. Experiment II^ — In transferring adults during the 

 spring of 1918 to new hickory wood to continue a large colony, a piece of 

 oak was unintentionally left in the cage. This cage contained six large 

 hickory logs 4 to 6 inches in diameter and 5 feet long. The oak log 

 was 3 inches in diameter and 4 feet long. 



During September, 1918, work of Cyllene was noticed on this piece of 

 oak, and in the spring of 1919 it was separately caged. Five adults 

 emerged in April — all very small, much below normal size. 



Two females and one male were transferred to a cage containing only 

 oak; one pair to a cage of oak and hickory. These cages were examined 

 July 16. Neither wood of the selection test was infested, but the oak 

 wood on which two pairs were caged contained a few very small larvae. 



11^^ — ^To test the influence of host selection on the condition of host. 

 In April, 19 18, two males and two females from hickory were isolated in 

 a cage containing a piece of grape and a piece of hickory of equal size — 

 the grape of optimum cut, January, 19 18, the hickory less favorable, 

 November, 191 7. Examination in July showed the grape to be heavily 

 infested while the hickory contained very few larvae. 



