COLEOPTERA SCOLYTID^E. 



109 



makes a slight burrow in the bark. Having scooped out a circular 

 chamber, she then returns to the outer world, and re-enters the 

 chamber accompanied by the male. In this chamber copulation takes 

 place, after which the female proceeds to bore farther into the stem, 

 almost at right angles to the first-scooped portion of the chamber. 

 The main or mother gallery is therefore a straight line, with a bend at 

 the bottom, or entrance, somewhat resembling a golf club (fig. 102). 

 The total length of the mother-gallery is about three inches, and there 

 are generally two or three air-holes directly over the gallery. In 

 about ten or twenty days after 

 the first eggs have been de- 

 posited the larva? hatch out, 

 and proceed to eat their way, 

 more or less at right angles, to 

 the mother-gallery. At first, 

 therefore, the markings are 

 very characteristic, as in fig. 

 102 ; but later on the larval 

 markings are very much inter- 

 mingled, as in fig. 103, which 

 is a photograph from a por- 

 tion of bark, and shows the 

 intermingling of larval gal- 

 leries from several adjacent 

 broods. 



At first the larval galleries 

 are very fine and thread-like, 

 but as the grubs enlarge the 

 galleries widen, and pupation 

 takes place at the end of the larval gallery. It should be noted that 

 both larval and mother galleries are always made in the bark, and 

 never in the wood, though the frass always lies on the wood after the 

 removal of the bark. Thus the beetle in question is a hark beetle. 



The beetles escape from the pupal chamber by making direct exit- 

 holes, and thus the numerous flight-holes in the bark indicate that 

 a new generation has escaped. 



The beetles arising from the first-deposited eggs hatch out in about 

 three to five weeks, generally towards the end of June, and these 

 early hatched beetles, on quitting the galleries, deposit eggs in the 



Fig. 103. Portion of bark of Scots pine, showing two 



mother-galleries and larval workings. 



