1900^ GREATER ASH-BARK BEETLE. 17 



and amount of the very irregular tunnellings, showed that much harm 

 was being done to Ash of considerable size, and, from the presence of 

 H. crenatus beetles, showed this species to be the cause of the mischief. 



The beetles are usually the fifth of an inch or rather less in length, 

 short and broad in form, and black, rather shiny, and with few hairs. 

 The thorax slightly broader than long, narrowed and coarsely punc- 

 tured in front, less closely punctured behind. Wing-cases deeply 

 striated, with the spaces between roughly tuberculated ; legs black or 

 dark, feet usually lighter ; antennae (horns) clubbed, and rusty or dark 

 rusty-coloured. 



These beetles, which are described by Herr Eichhoff as being the 

 largest amongst the allied species,* are very easily known from 

 H. fraxini by their much greater length, their shiny black colour, 

 without any mottling of grey above, and also the very observable 

 tuberculation of the wing-cases. Tliey vary sometimes both in colour 

 and shape (see figure, p. 16, where " 1 and 2 " are given as they are 

 usually found, magnified, with lines showing natural length and ex- 

 panse of wings ; and " 3," of a smaller size and redder colour, some- 

 times occurring) ; but the tuberculed wing-cases and the absence of 

 all paler mottling on the upper surface are sure guides by which to 

 distinguish this species from H. fraxini. 



The method of attack is much like that of the " Common" Ash-bark 

 Beetle ; the female beetle pierces a short tunnel through the bark, and 

 beneath it in the " cambial region" (that is, where the new wood 

 forms yearly between the outer part of the wood and the inner part of 

 the bark) she tunnels her galleries for egg-laying. These are generally 

 short compared to those of H. fruxini, and sometimes two-armed, but 

 these, it may be, differing from each other in length, and sometimes 

 only one branch is present. 



Along the sides of these galleries the white eggs are laid, often at 

 considerable distances one from the other. The white, legless grubs 

 on hatching out, gnaw their tunnels, at first at right angles to the 

 mother-tunnel ; but later these tunnels, which increase in size as 

 needed to accommodate the increasing size of the grubs, wind irre- 

 gularly, even so as to run parallel with the mother-gallery, and in 

 smaller stems may be continued so far in length as almost to ring 

 the tree. 



The above points — that is, the shortness of the mother-galleries, 

 the small numbers of little chambers for eggs along their sides, 

 and the very irregular twisting of the maggot -tunnels — are given in 

 the following figure, taken from some large pieces of Ash bark 

 showing good examples of workings of H. crenatus, kindly given me by 



* ' Die Europaischen Borkenkafer,' von W. Eichhoff, p. 134. 



