2o8 Journal of Agricultural Research voi. xxn, no. 4 



Later winter or fall cuts in which the inner bark has remained sappy are 

 most suitable. Species of wood which season more slowly, due to thick 

 bark, must be cut earlier. 



The time of first emergence varies greatly with locality, but the species 

 is everywhere one of the first cerambycid beetles to fly in the spring. 

 The larvse in all cases feed immediately beneath the bark, only entering 

 the sapwood in late summer to make a shallow pupal cell. Pupation 

 and transformation to the adult usually take place in the fall. 



The present experiment was started at Kanawha Station, W. Va, Dr. 

 Hopkins felled a juniper (Juniperus) in October, 1914. This tree was 

 infested the following spring and shipped to East Falls Church, Va. 

 The colony has since been continued in juniper and one host strain has 

 been produced in Douglas fir (Pseudotsuga) . This particular color 

 variety had never been recorded from Douglas fir. 



Pseudotsuga. Experiment VIII^— April 11, 191 7, three females and 

 two males were isolated on a piece of Douglas fir cut April i . Eggs were 

 laid and young larvse entered the bark, but many died during the summer 

 and only two constructed pupal cells. One adult was secured next 

 spring. The fact that this wood was too green and that it seasons very 

 slowly may have caused a higher mortality than would otherwise have 

 occurred. 



May 29, 191 7, twelve larvae and June 15, nine larvse were transferred 

 to this host, the wood then being better seasoned. March i, 1918, five 

 adults — four females and one male — were removed from pupal cells. 

 The remainder of the larvae had died. Two females and one male were 

 used to continue the colony by caging on Douglas fir, cut in October, 

 19 1 7. A good infestation was secured. A piece of juniper cut during 

 January, 1918, had also been placed in tliis cage but was not infested. 

 In January, 1919, four adults were removed from the logs — three males 

 and one female. The remainder had all died and these were very weak 

 and below normal size. One pair was recaged on juniper cut in January 

 and Pseudotsuga cut in November. July 30, 19 19, the sticks were 

 examined, but no infestation was found in either wood. 



CONCLUSIONS 



This juniper form of Hylotrupes ligneus, after feeding part of a year in 

 a new host, showed a preference for the new host. 



A high percentage of mortality occurred in producing the new host 

 strain, which finally died out. 



HYEOTRUPES EIGNEUS, PSEUDOTSUGA FORM. EXPERIMENT XXXV 



This form of Hylotrupes ligneus is much darker and more hairy than the 

 preceding. It has been recorded only from Douglas fir. Its biology is 

 essentially similar to that of the juniper form except that the adults 

 emerge somewhat later. It is known from the Rocky Mountain region. 



