10 PITH-EAY FLECKS IX WOOD. 



BETULACEiE. 

 Ck)mmon name. Botanical name. 



River birch Betula nigra Linn. 



Paper birch. Betula papyri/era Mai-sh. 



"WTiite birch Betula populifolia Mai-sh. 



Hornbeam Ostrya virginiana (Mill.) Koch. 



Lanceleaf alder Alnus acuminata H. B. K. 



ROSACE^.. 



Serviceberry Amelanchier canadensis (Linn.) Medic. 



Western serviceberry Amelanchier alnifoUa Nutt. 



Mountain ash Pyrus americana (Marsh.) de C. 



Narrowleaf crab Pyrus angustifolia Ait. 



Wild apple Pyrus malus Lian. 



Oregon crab Pyrus rivularis Dougl. 



Elderleaf mountain ash Pyrus sambucifolia Cham. & Schl. 



Allegheny sloe Prunus allegheniensis Porter. 



Wild plum Prunus americana Marsh, 



Sweet cherry Prunus avium Linn. 



Sour cherry Prunus cerasus Linn. 



Western choke cherry Prunus demissa (Nutt.) Walp. 



Bitter cherry Prunus emarginata (Dougl.) Walp. 



Garden wild plum Prunus hortulana Bailey. 



Holly leaf cherry Prunus ilicifolia (Nutt.) Walp. 



Wild red cherry Prunus pennsylvanica Linn. 



Black cherry Prunus serotina Ehrh. 



Choke cherry Pi'unus virginiana Linn. 



Summer haw Crataegus aestivalis (Walt.) Torr. & Gr. 



Dotted haw Cratxgus punctata Jacq. 



ACERACEiE. 



Striped maple Acer pennsylvanicum Linn. 



Red maple Acer ruhrum Linn. 



Silver maple Acer saccharinum Linn. 



TILIACE.E. 



Basswood Tilia americana Linn. 



GEOGRAPHIC DISTRIBUTION OF THE CAMBIUM MINER. 



The geographic distribution of the cambium miner can not be 

 definitely fixed at present, because of the uncertainty of the source 

 of many of the wood samples examined and of the difference in sus- 

 ceptibility of the same host in different situations. Nordlinger's list 

 of woods includes species that grow throughout a vast area, and 

 shows that pith flecks occur in wood of all tropical and temperate 

 regions. Many European species examined contained them. Fur- 

 ther investigations of foreign woods will doubtless increase the num- 

 ber of host trees. From the list of indigenous trees given it is seen 

 that the insect producing these flecks is quite generally distributed 

 over the United States. The extent to which different genera and 



