THE GENUS DENDROCTONUS. 75 



burning of the infested bark during the principal period of larval 

 development and during the inactive or overwintering periods, if such 

 are found within its range. 



This species has not been recognized within the United States, but 

 it is not improbable that it may be found in the pine forests of south- 

 ern Arizona and New Mexico. 



The writer has identified thirty-six specimens received from Prof. 

 A. L. Herrera and Dr. S. J. Bonansea, collected from pine in Ame- 

 cameca, Michoacan, and Tacubaya, Mexico. 



BIBLIOGRxlPHY. 



Hopkins, 1906c, p. 80; Hopkins, 1909, pp. 97-99. 



No. 7. THE LARGER MEXICAN PINE BEETLE. 



{Dendroctonus parallelocollis Chap. Figs. 37-39.) 



The larger Mexican pine beetle is a somewhat elongate, cylin- 

 drical, dark brown to black barkbeetle, 5 to 6 mm. in length, with 

 broad, deeply grooved head; broad prothorax, with sides nearly 

 parallel and but slightly narrowed toward the head, and elytra with 

 dense, moderately coarse rugosities, the declivity with coarse punc- 

 tures and long erect hairs. (See fig. 37.) It attacks living pine 

 trees in Mexico, excavating coarse, slightly winding, longitudinal 

 or oblique and sometimes branched egg galleries (fig. 38) through 

 the inner bark. The larval mines are evidently concealed beneath the 

 inner layers of bark, and the larvae evidently transform to pupae in 

 separate cells in the outer bark. It is usually associated with the 

 smaller Mexican pine beetle in the same tree. 



Very little appears to be known in regard to the seasonal history 

 of this species, but it is so closely related to the Colorado pine beetle 

 in general characters that it is probably quite similar in seasonal 

 history as well as in habits and in the character of injury to the 

 trees, except in such minor differences as may be brought about by 

 its more southern range. It is evident that the unhealthy and dying 

 condition of the pine in certain localities in Mexico, which has been 

 reported from time to time, is caused largely by this species and by 

 the smaller Mexican pine beetle. 



Ten specimens of the beetle and one of" the galleries, received from 

 Prof. A. L. Herrera, collected in Michoacan, etc., have been examined 

 and identified by the writer. 



If this species is found overlapping the range of the Colorado pine 

 beetle, it can be distinguished from that species by the slightly 

 longer prothorax, with sides more parallel and less narrowed toward 

 the head. 



BIBLIOGRAPHY. 



Hopkins, 1906, pp. 80-81; Hopkins, 1909, pp. 99-101. 



