64 



The subject is one of considerable interest and promise, but fraught 

 with difficulties. In the writer's opinion, several years of careful study 

 of different species, and particularly of most of those which have re- 

 cently been under observation, together with all of the elements which 

 tend to produce an increase or decrease in their numbers, would be 

 productive of definite conclusions as to the cause of these fluctuations. 



FOOD PLANTS AND INJURY OF NORTH AMERICAN SPECIES OF 



AGRILUS. 



By F. H. Chittenden. 



At the time of the publication of an article on the bronze birch borer, 

 Agrilus anrius Gory, in Bulletin Xo. 18 (n. s.. pp. 44-51). which appeared 

 in January. 1899, it was intended to include some observations on the 

 habits of other species of Agrilus, together with a summary of the 

 known host trees of other Xorth American species, and the paper 

 which is presented here was prepared with that intention. Lack of 

 space, however, prevented its publication at that time, and it is now 

 presented as a separate article, together with a few additions resulting 

 from observations during the past season. 



The Buprestid genus Agrilus includes five species which have been 

 reported to be injurious to birch and poplar, chestnut and oak, Lombardy 

 poplar, raspberry and blackberry, and pear trees, respectively : and there 

 is strong likelihood that some others, which will receive mention in this 

 article, may assume destructive habits at any time. In the notes which 

 follow special mention of injury by different species of Agrilus a sum- 

 mary is given of all the North American species whose food habits are 

 known, together with their host plants, dates of appearances, and refer- 

 ences to published records of their habits. 



In the preparation of this portion of the article the writer has made 

 free use of Divisional notes and is particularly indebted to Mr. E. A. 

 Schwarz for kindness in placing at his disposal many unpublished notes 

 based on the observations of the late H. G. Hubbard and himself on 

 the food plants of species mostly of the Southwestern States. 



THE BRONZE BIRCH BORER. 



As the subject of the biology and remedies to be applied to this 

 species has lately become a special study on the part of Prof. M.V. Sliu- 

 gerland, of the Cornell University Agricultural Experiment Station, it 

 has not been given the same attention at this office since the publica- 

 tion of the writer's former article on this insect that would otherwise 

 have been given it. A few facts, however, have been reported by cor- 

 respondence and others have- come under observation through office 

 rearings which are of interest and which may be appropriately recorded 

 here in connection with what will be said concerning other species of 

 the same o-enus. 



