2IO Journal of Agricultural Research Voi. xxn. no. 4 



were isolated with redwood (XL) females, but in no case did copulation 

 take place. 



The females of the j'uniper form mated with males of the sequoia form 

 were caged on juniper cut in January, 19 18, and good infestations were 

 secured. 



CONCLUSIONS ON THE ENTIRE HYLOTRUPES EIGNEUS GROUP 



The experiments on the Hylotrupes ligneus group, as mentioned above, 

 were conducted primarily for the study of its color variation, and not a 

 great deal of attention was devoted to the host-selection principle. The 

 experiments cited show that among all the color varieties of this group 

 there are probably two good species, the darker and more hairy Douglas 

 fir form representing one species and all the other forms another. These 

 two species absolutely refused to mate, but the varieties from sequoia 

 and juniper were successfully crossed. 



NEOCLYTUS CAPRAEA. EXPERIMENT VI 



Neoclytus capraea is known to inhabit the eastern and central western 

 United States, extending its range south and west into Arizona. It has 

 been recorded from only two hosts, ash (Fraxinus) and white oak 

 (Quercus alba of the Rocky Mountains). In the eastern United States 

 it has never been found in oak. The condition of the wood necessary 

 for oviposition by these beetles must be exactly right. It must have 

 been freshly cut and the inner bark must be still moist and sappy. Should 

 this inner bark be slightly dried the females will not oviposit on it unless 

 forced to do so. Logs cut about two months before the flight period 

 are preferred to older cuts or those cut during flight. Trees cut as 

 early as November 15 are sometimes infested, but not commonly. 



The adults fly very early in the spring in this locality (Falls Church, 

 Va.), about the last week in March and the first two weeks of April. The 

 larvse feed chiefly in the wood proper. Mining beneath the bark for a 

 short time, they then enter the sapwood and later the outer heartwood, 

 extensively honeycombing it. Pupation and transformation to the adult 

 take place in the early fall. 



VI.— March 26, 1915, twelve adults were taken as they emerged from 

 an ash log and were caged on freshl}' cut wood. A good infestation was 

 secured, and the colony has since been continued in ash. 



In the spring of 19 19 no adults emerged. All the larvae remained 

 over as larvae in their pupal cells until the fall of 19 19, when they trans- 

 formed to adults and emerged in 1920. No explanation for this can be 

 offered unless the logs were too moist in the early part of the summer 

 so that the larvae did not develop properly. Excess humidity or exces- 

 sive desiccation have both been found to produce retardation in devel- 

 opment of larvae in small isolated cages. This insect is one of the most 

 regular of those reared, in the time of emergence and development of 



