SMALLER PINE BEETLE IN ABERDEENSHIRE 



353 



the suture are present all the way down to the very apex 

 (see Fig. i); in M. piniperda the tubercles on the second 

 interstice on each side of the suture, while present most of 

 the way, are absent at the apex : this part of the inter- 

 stice in piniperda is not only smooth but looks somewhat 

 hollowed out (see Fig. 2). 

 This difference, though at 

 first somewhat difficult to 

 detect, is later seen to be 

 well founded, and after 

 practice quite obvious. 

 With a lens also one may 

 notice a difference in the 

 position of the teeth borne 



on the hind tibiae of the Fig. 3.— Hind leg of M. piniperda. 



two beetles. In the case «, = base of tibia; 6, = middle of tibia; c, = apex 

 . . of tibia. 



of M. piniperda the upper 



tooth is below the middle of the tibia, while in M. minor 



the upper tooth is at the middle (see Figs. 3 and 4). 



There is no possible confusion, however, in the pattern of 

 the mother and brood galleries of the two beetles. As is 

 seen in Fig. 5, the mother gallery oi M. piniperda is vertical, 



and the larval galleries, 

 which are somewhat 

 crowded together, run 

 transversely. In M. minor 

 the mother gallery is 

 two - armed and in the 

 transverse direction (over- 

 crowding may result in 

 a somewhat irregular 

 pattern), while the larval 

 galleries run upwards and 

 downwards, and are not 

 so close to one another. 

 The mother galleries of M. minor also cut more deeply 

 into the sapwood, and the larval ones are much shorter 

 than those of M. piniperda. The borings found by me at 

 Aboyne were very typical examples of the work of M. 

 48 2Q 



Fig. 4. — Hind leg of M. minor. 



a = base of tibia; 6 = middle of tibia; c=apex 

 of tibia. 



