212 Journal of Agricultural Research voi. xxn, no. 4 



MOLORCHUS BIMACUI,ATUS. EXPERIMENTS IX, X, AND XXXVI 



Two forms included under Molorchtis bimaculahis Say have been 

 caged in these experiments, a large form from hackberry {Celtis occi- 

 dentalis Linn.), and a smaller form from dogwood (Cornus florida Linn.) 

 and maple (Acer) . They both are found throughout the eastern half of 

 the United States. From the observations on the biology of these two 

 forms they are regarded by the writer as distinct species. Both forms 

 prefer early fall cuts of wood, but the Celtis form requires much drier 

 seasoned material. 



MOLORCHUS BIMACULATUS, CORNUS FORM. EXPERIMENT IX 



The Comus form feeds in a great variety of eastern hardwoods. It 

 has been reared from Hicoria, Acer, Juglans, Ouercus, Liriodendron, 

 Comus, Cercis, and Castanea. The larva feed beneath the bark, making 

 a long, curved pupal cell in the wood. By September they have trans- 

 formed to adults, which emerge early in May at Falls Church, Va. The 

 flight is very regular, nearly all emerging at the same time. The adults 

 are much smaller than those of the hackberry form. 



In May, 19 16, adults were reared from dogwood collected at Falls 

 Church, Va. They were recaged on dogwood cut in April, but a poor 

 infestation was secured from which only five adults emerged in 191 7. 

 These five adults were caged on September and November cuts of dog- 

 wood and redbud (Cercis canadensis Linn.) . A good infestation occurred 

 in the dogwood, but no larvae were found in redbud. 



May I, 191 7, five adults were isolated in a cage containing November 

 cuts of dogwood and maple. The maple was not infested, but many 

 larvae were found in the dogwood. 



In April, 1918, 1919, and 1920, the colony was continued only in dog- 

 wood. No selection tests were made. 



MOLORCHUS BIMACULATUS, ACER FORM. EXPERIMENT XXXVI 



This form in all respects is similar to the dogwood variety IX. 



Infested limbs collected at Falls Church, Va., were caged in the sum- 

 mer of 1916. 



May I, 191 7, five adults were caged on branches of maple and dog- 

 wood cut in September and November. The maple was infested but no 

 larvae entered the dogwood. 



In 19 1 8 many adults emerged from the maple and were recaged on 

 October cuts of maple and dogwood. Eggs were laid on the maple, but 

 the cage unfortunately was overlooked and became so dry that none of 

 the eggs hatched. 



MOLORCHUS BIMACULATUS, CELTiS FORM. EXPERIMENT X 



The form in hackberry, in which the adults are much larger, has been 

 reared only from this host. The larvae feed as in the dogwood or maple 



