FLAT-CELLED SHOT-BORER BEETLE. 193 



in the brood cells of saxeseni being broad and fiat, whilst 

 those of dispar are cylindrical borings, is not noticeable until 

 the wood is split open ; the beetles also are so far similar 

 that some knowledge of their special characteristics and the 

 use of a magnifying-glass are necessary to make sure of which 

 kind is under observation. 



Xi/lehorus saxeseni is somewhat elongate in shape ; the 

 females rather more than a line ia length, the males shorter 

 and rather broader. The females black (or sometimes of a 

 3'ellowish brown) with a small amount of grey hairs ; the 

 males wingless, much fewer in number than the females, the 

 brownish colour of a lighter shade, and the hairs longer. 

 This kind may be readily distinguished (see figures, pp. 185, 

 192) from X. dispar (the only species which at present there 

 may be occasion to distinguish them from here) by the female 

 of dispar having the thorax (or fore body) large in proportion, 

 and raised in the middle into a kind of hump, while the male, 

 which is only two-thirds of the length of the female in this 

 sijecies, is remarkable for being much wider in proportion, 

 and flat on the back. From all other species of Xt/leborus it 

 is considered that saxeseni ^^ xylographus may be distinguished 

 " by the very regular rows of small but sharp teeth upon the 

 declivity of the elytra." * 



The matured larva is in colour " yellowish white to yellow; 

 head darker, with dark brown mandibles and brown longi- 

 tudinal line ; . . . body stouter, thoracic segments much 

 larger, and head much smaller in proportion to body than in 

 first and intermediate stages ; segments and head sparsely 

 clothed with short fine hairs ; length about one line." t 



In the course of my own observations, on splitting one of 

 the pieces of Plum wood open, on July 28th, I found two 

 parties of maggots within about two inches of each other. 

 These were of different ages, whitish, and legless, and dis- 

 tinctly lobed, the head very shining white, or, in the older 

 specimens, with a faint yellowish tint (see figure 2, p. 192). 

 Whilst still alive or quite fresh the three first segments 

 appeared to me to be somewhat inflated below, and but 

 slightly corrugated above ; the others slightly lobed below, 

 and much corrugated longitudinally above. 



In this instance the cell was a flat cavity just inside the 



* See "Ambrosia Beetles of the United States," by H. G. Hubbard, in 

 ' Some Miscellaneous Kesults of Work of the Division of Entomology,' United 

 States Department of Agriculture, Washington, 18'J7, p. 24. 



t Minutely detailed description of the insect from egg to male and female 

 beetle will be found in the paper on " ' The Wood Engraver,' Ambrosia Beetle, 

 Xyleborus xylographus (Say), Xyleborus saxeseni (Eatz.)," by A. D. Hopkins, 

 Entomologist, West Virginia Agricultural Experiment Station, pp. '27-29 ; 

 published in No. 2 of 'Canadian Entomologist,' 1898. 



O 



