45 



the result that on November 10 some fragmentary specimens were 

 secured, among which was fortunately a male, which proved the species 

 to be Agrilus anxius Gory. 



The notes which follow concerning the occurrence of this insect on 

 birch at Buffalo have been brought together from 

 data kindly furnished by Mr. Adams, to whom great 

 credit is due for his zeal in the matter. 



Injury can be detected in the trunk by a reddish 

 discoloration from one- quarter to one inch in width, 

 this being caused by the exudation of sap and the 

 ejectment of excrement. Another indication of the 

 insect's presence is the dying of the trees at their 

 tops. The insect appears to attack the tree at first 

 among the larger branches at a considerable height, 

 causing the tree to die at the top while the remaining 

 lower branches keep green. Its presence is also 

 manifested by the uneven, wavy appearance of the 

 bark, which shows more or less regular spiral ridges 

 on the smaller branches. (See fig. 15.) The borer 

 larva makes an opening through the outer bark of a 

 size a little larger than a pin head. It then mines 

 farther on beneath the bark, and there rests in a cav- 

 ity which it prepares for its transformation not far 

 from this discoloration. In cases where the inner bark 

 is not thick enough, or where it happens to be dead, 

 the larva enters the wood instead of making, as be- 

 fore, its cavity for pupation in the bark, being inclined 

 apparently to avoid dead tissue, either wood or bark. 



In the samples of work received the galleries of 

 this borer larva run so closely together, often cross- 

 ing and recrossing in such endless confusion that it 

 is impossible to trace any individual burrow. A 

 sample of the work is illustrated at figure 16. The 

 galleries made by the mature larva measure about 

 an eighth of an inch in width (3 mm.). It is the nor- 

 mal habit of the larva to leave its castings in the 

 galleries as it works, as shown in the illustration. 



The larva, as a rule, enters the wood in the fall and 

 there constructs a cavity, which probably serves the 

 purpose of a pupal cell, in which it passes its ulti- 

 mate transformations in late spring or early summer. 

 Within this cell the larva passes the winter. In those 

 individuals before the writer the caudal extremity of the larva is pointed 

 downward, and the head and thoracic and first abdominal segments are 

 doubled back upon the other segments in a position which he has not 

 observed in any other larva, but this is probably the normal habit of 



&-^i 



Fig. 15.— Work of Ag- 

 rilus anxius on limb of 

 "white birch — somewhat 

 reduced (original). 



