690 



The Large Brown Pine Weevil. 



[FEB, 



This insect, Hylobius abietis, one of the most grievous pests 



in forestry, is in our country the cause of the dying away of 



young coniferous plants, acres of which 



The Large Brown may h ave to be re-planted because of the 

 Pine Weevil. * r . . 



weevil attack. Ihe larvae or grubs live in 



the stumps and roots of felled conifers, and therefore do little 

 actual harm ; the harm is done by the adult beetles, which gnaw 

 the bark of the stem of young plants and the younger shoots of 

 older plants. 



Plants attacked. — The plants attacked by the adult are 

 Scots pine, Weymouth pine, spruce, larch, Japanese larch, 

 silver fir, and Douglas fir. It is characteristically a conifer pest, 

 but if the coniferous crop be not pure but mixed with broad- 

 leaved species such as oak, alder, birch, these latter may also 

 be attacked. 



Characteristics of attack.— (a) Pieces may be bitten away 

 here and there all down the young plant. The damage may 

 extend as far as the cambium layer. Very young plants 

 •may be more or less completely barked. (J?) Drops of resin may 

 be found exuding from the wounds. These drops dry into 

 rough masses over the stem. (c) The dying off of attacked 

 plants. 



Description of Insect. — The beetle measures up to half an inch 

 in length. It has a marked proboscis, with the kneed-antennae 

 springing from near its apex. The colour is dark brown, with 

 yellowish or golden hairs or scales on various parts of the body, 

 but these are specially marked on the wing covers, where they 

 form bands ; in old beetles, the scales may have been rubbed off. 



The larvae are yellowish-white in colour, legless, with brown 

 heads and biting jaws ; they have a curved form, and when 

 full grown measure up to half an inch. 



Life history. — The beetles choose as their favourite place for 

 egg-laying the stumps and thicker roots (exposed or below the 

 surface) of felled pine and spruce. The eggs are laid singly, 

 and the grubs on hatching gnaw long tunnels between the wood 

 and the bark, these tunnels increasing in width with the growth 

 of the grub ; behind the grub the tunnels are filled with frass 

 from the boring. When full grown the grub gnaws out a bed 

 in the youngest wood layers, and here, under a cover of sawdust 



