118 BULLETIN 14 5, UNITED STATES NATIONAL MUSEUM 



Type locality. — Of bilineatus, "America " ; present location of type 

 unknown to writer. Of flawolineatus, North America ; type presum- 

 ably in the Dejean collection. Of bivittatus, Canada ; type presum- 

 abty in the British Museum. Of aurolineatus, North America ; type 

 presumably in the Dejean collection. 



Distribution. — This species has a wide distribution, being found in 

 eastern Canada (Ontario and Quebec), and throughout the United 

 States from Maine westward to the Rocky Mountains, and southward 

 to Texas. Material has been examined from various localities in 

 the following States: Arkansas, Connecticut, District of Columbia, 

 Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Maryland, Massa- 

 chusetts, Michigan, Missouri, New Hampshire, New Jersey, New 

 York, North Carolina, Ohio, Pennsylvania, Rhode Island, Texas, 

 Virginia, West Virginia, and Wisconsin. 



Variations. — This species shows considerable variation in size, as 

 a result of their food plant becoming too dry, and causing the larvae 

 to pupate prematurely. The pubescence forming the lateral spaces on 

 the pronotum and the vittae on the elytra varies from golden yellow 

 to white, with all intermediate shades. Usually these pubescent 

 vittae are entire, extending from the basal depressions to the tips of 

 the elytra, but frequently examples are found in which the vittae are 

 only indicated near the basal depressions. 



Hosts. — Attacks white oak (Quercus alba Linnaeus), red oak 

 (Quercus rubra Linnaeus), black oak {Quercus velutina La Marck), 

 scarlet oak {Quercus coccinea Muenchhausen), burr oak (Quercus 

 macrocarpa), and chesnut (Gastanea dentata (Marshall) Bork- 

 hausen). It will probably attack any of the oaks, and becomes 

 very injurious to trees which have been weakened by other insects, 

 plant diseases, or climatic conditions. Some writers record this 

 species as killing more oaks than any other species of insect so far 

 discovered. All of the records of bilineatus recorded from beech 

 (Fagus sp.) should probably be referred to the variety carpini Knull. 



This is one of the best known species of Agrilus found in North 

 America, and on account of the great amount of damage it causes 

 to oak and chestnut trees it has received the attention of entomolo- 

 gists in all parts of the country. It is usually recorded in the 

 economic literature under the " Two lined chestnut borer," which 

 was adopted as the common name for this species by the American 

 Association of Economic Entomologists. Mannerheim (1837) de- 

 scribed this species as flavolineatus from a specimen under that name 

 in the Dejean Collection, and Gory (1841) redescribed it under the 

 name of aurolineatus from the same specimen. Essig (1926) records 

 this species as girdling oak trees in Colorado, but this is incorrect. 



