132 Highland Insects. 



tion ; whilst a male from a full-fed oak-bred larva is of great 

 bulk, and bears huge branching dentate mandibles. It is not, 

 however, only the mandibles that are subject to this variation ; 

 all sexual developments, such as cornuted processes on head 

 or thorax, swelling of hind femora, dilatation of the head or 

 front tarsi, spining and curving of the hinder tibiae, etc., come 

 under the same law. 



A very marked instance of a frequently observed habit of 

 insects — viz., that of their frequenting places similar in colour 

 to themselves, was constantly forced upon my eye at Rannoch 

 by Rhagium indagator, a Longicorn beetle apparently peculiar to 

 this part of our country, and belonging to a genus very de- 

 structive to timber, the fat, flat-headed larvae swarming under 

 pine-bark in all directions, and committing great havoc. This 

 insect is of a mottled grey colour, strikingly similar to the 

 lichen-covered bark of the larch, on which tree (and never on 

 the dark black pine) I constantly found it, beetle and bark 

 being so precisely alike in hue and markings, that it was 

 possible absolutely to sit on the log and yet not see the insect. 

 On these logs, and. under the bark, the very flat Pytho depressus 

 (another species added to our catalogue from Rannoch) is oc- 

 casionally to be found — a beetle which, although apparently 

 bulky when viewed from the upper side, is most eminently 

 adapted for slipping into the narrowest cracks. Its voracious, 

 elongate larva, armed at the hinder apex of the upper side with 

 two recurved hooks, for the purpose of obtaining a fulcrum, is 

 found under bark, where it preys upon the larvae of Rhagium, 

 and other true wood-feeders. 



Running about quickly, in company with Pytho and the 

 fragile Dirccea, Clerus formicarius, a curiously banded and varie- 

 gated species, strongly suggestive of a large exotic ant, might 

 often be seen ; its larva being of similar sub-cortical habits to 

 that of the Pytho. 



The freshly-cut stumps of fir-trees, fragrant with exuding 

 turpentine, act as splendid traps for many beetles, Astinomus 

 often settling on them, and a flattish, dull black Longicorn 

 allied to it, Asemum striatum, called " the soft timber man M 

 by the wood-cutters, being very plentiful. Ripping the bark 

 off these and older stumps disclosed numerous colonies of 

 Xylophagous Goleopt&ra, with their larva) and attendants ; the 

 species of Hylastes and Hylurgns being very abundant in 

 deeply cut narrow channels worked in the underside of the 

 bark, at the end of each of which the change to pupa takes 

 place, the perfect insect drilling a neat round hole through 

 which it escapes to the surface. Two species of fys (one 

 yellow, the other black, with red spots), and three or four of 

 the linear Rhizophagus, abound also in these galleries ; syco- 



