2i8 Journal of Agricultural Research voi. xxn,Na4 



Hofer. It has since been continued in gooseberry cut at Colorado 

 Springs in the fall and shipped to Falls Church; in addition, several 

 other host strains were produced. Only one generation of adults occurs 

 each year. 



May 20 to June 10, 1916, adults emerged and 47 were isolated in a 

 cage containing gooseberry, chestnut, and wild cherry, all cut in the 

 preceding fall. The gooseberry stems were heavily infested, a few larvae 

 were present in the wild cherry, but none were found in the chestnut. 

 The colony has since been continued in gooseberry. 



Prunus. Experiment XXVI ^ — The infested wild cheiry twigs 

 (described above) were caged separately, and in June, 191 7, four adults 

 emerged. These were caged again on a fall cut of wild cherry. The 

 infestation was not very good, and only six adults were secured in 19 18; 

 these were recaged on the same wood, but no infestation occurred. 



Castanea. Experiment XXVI^ — As previously stated, the chestnut 

 sticks were not infested in 1916 when caged with gooseberry. In June, 

 191 7, nine adults were isolated on chestnut cut in November, 19 16, and a 

 good infestation was secured. June, 1918, nine adults emerged and were 

 isolated in a cage containing chestnut and gooseberrry cut in November, 

 1917. Later examination showed only the gooseberry to be infested. 



LiRiODENDRON. EXPERIMENT XXVIl — ^June 5, 191 7, eight adults 

 from gooseberry were isolated on tulip cut in November, 19 16. Five 

 adults emerged from these sticks in 19 18 and were isolated in a cage 

 containing tulip and gooseberry cut in November, 191 7. Neither wood 

 was infested. 



HYPERPLATYS MACULATUS, CASTANEA HOST STRAIN. EXPERIMENT XXIX 



In April, 19 16, at Falls Church, Va., branches of chestnut (Castanea) 

 containing larvse in the pupal cells were collected and caged. Some of 

 the adults emerging in June were isolated with chestnut cut in March, 

 1916, and the others isolated in a cage containing chestnut and dogwood 

 (Comus) branches cut in March, 19 16. Those isolated on chestnut 

 alone attacked this wood although it was a late cut. Those isolated on 

 the two woods infested both, but the dogwood more heavily. Nothing 

 more was done with the chestnut form. Many adults emerged that fall. 



CoRNUS. Experiment XXIX ^ — ^The dogwood sticks were then caged 

 separately and adults secured in September, 1916, and more of them in 

 June, 191 7. Those emerging during the latter period were recaged on 

 August and November cuts of dogwood, but no infestation occurred. 



CONCLUSIONS 



In Hyperplatys maculatus host selection occurs to a certain degree ; 

 but this beetle behaves differently from most of the other species 

 tested. Thus the tulip form (experiment XXVIII) in 1 9 1 7 chiefly selected 

 the same host, but it also oviposited on gooseberry. This gooseberry 

 colony, however, was weak, and a high mortality in larvae occurred. 



