I 68 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



the help given by the characteristic pattern of its brood-galleries, 

 any interested forester will be able to run it down. 



The Adult Beetle (Fig. i): — Pityogenes chalcographus measures 

 from over ^ to ~~ inch. The colour of a beetle which has 

 come out into the open is black-brown to reddish-brown. A 

 very helpful point in determination of the beetle is that generally 

 it shows two shades of colour, the thorax and the front part 

 of the wing-covers being dark (black-brown) and the hinder 

 part of the body pale copper-coloured or light chestnut. The 

 antennae — which are very small and end in a round club 

 (visible with a lens) — and the legs are yellow-brown. 



The head can scarcely be seen from the upper surface. 

 The thorax (it is really only the front part of the thorax which 

 is visible from above) is longer than broad ; if one looks down 

 on it, with a lens, the front part is seen to be rough or granular 

 and the hind part to be very finely punctured ; a longitudinal 

 central line and a spot on each side (not easy to see) are quite 

 smooth. The wing-covers show rows of fine punctures which 

 die away behind the middle, especially leaving the sides smooth. 

 At the hind end the wing-covers show a steep slope with a 

 furrow on each side of the suture ; on each side of the slope 

 there are three spines or teeth ; these teeth are directed slightly 

 inwards and are best seen if the beetle be examined from the 

 side. The teeth are equidistant and almost of the same size. 

 For experimental or other reasons the sexes may be distinguished 

 on careful examination, thus : — 



The larvae are typical Scolytid larvae, legless, with brown 

 horny head and jaws, and wrinkled white-yellow bodies ; the body 

 is slightly thicker at the front joints. The pupae are yellow- 

 white, and are found in beds at the end of the larval galleries. 



Nature of the brood-galleries. — P. chalcographus is polygamous. 

 The male enters the bark from the outside and excavates a 

 pairing-chamber. Typically this pairing-chamber is in the 

 middle of the bast layers. Here mating takes place with four 

 to eight females, each of which proceeds to gnaw a gallery for 



