226 



PROTECTION AGAINST INSPECTS. 



The chief swarming 



Fig. yi. — Scots piue root 

 bored by H. ahietis, L. 



a Boring free from wood- 

 dust. 



b Boring full of wood-dust. 



c Loiigitudiual suction of 

 pupal chamber. 



d Transverse section of 

 pupal chamber. 



c Flight hole. 



/ Entrance to pupal cham- 

 ber closed with bitten 

 wood. 



h. TAfe-histnri/. 



period of this beetle, which Uves from 

 1 to 2 years, is in the spring or early 

 summer (May or June) ; but jmiring 

 and reproduction go on throughout the 

 whole of the warmer season up to Sep- 

 tember, so that no real period for 

 swarming exists. Copulation generally 

 takes place on the ground. 



Tlie eggs are laid from May to Sep- 

 tember on stumps and roots of the 

 Scots pine and spruce, preferably on 

 those of trees felled about 18 months 

 before. The under-surface of roots — 

 and especially of those ^Yhich project out 

 of the ground — is preferred. Hiber- 

 nating beetles continue egg-laying in 

 the spring. 



The larvae appear after 2 to 3 weeks, 

 and up to the middle of October eat gal- 

 leries sometimes a metre long (Fig. 91) 

 in the bast and sap wood of the stumps 

 and roots ; the burrows continually 

 increase in breadth, and are tilled with 

 wood-dust. The larvae, at least those 

 which have been hatched in the autumn, 

 pass the winter at the end of these 

 galleries. They do no injury of any 

 economic importance, their sources of 

 food being confined to valueless wood. 



In the follow ing spring,af ter having been 

 dormant for about 9 months, the larvae 

 pupate in the stump or roots, in a cocoon 

 constructed of wood-fibres and boring- 

 dust. The pupal state lasts about 2 to 3 

 weeks. The perfect insects emerge from 

 May till September of the second year. 

 The period of disclosure thus extends 

 over four months, corresponding to the 



