72 ON THE HYLOBIUS ABIETIS OR FIR WEEVIL. 



ON THE HYLOBIUS ABIETIS OR FIR WEEVIL. 



By John M. Aitken, 24 St Andrew Square, Edinbnrgli. 



[Premium — Tlu Minor Gold Medal.'] 



All the information and experience that can be brought to bear 

 on matters affecting our supply of home-grown timber, either in 

 the way of improving the existing plantations or in connection 

 with the formation of new ones, are necessary at the present time 

 when we are constantly being reminded that the foreign supply 

 cannot always last ; and it is with the view of adding, if possible, 

 to our present knowledge in the latter respect that the reporter 

 begs to submit the following paper dealing with the Hylobius 

 abietis or fir weevil, the damages caused by it to young planta- 

 tions, and pointing out what occurs to him as the best mode of 

 preventing these damages. The facts stated are the result of 

 close personal observation, and the reporter believes that by 

 treating of one insect (and that one of the most destructive to 

 forest trees) in a practical manner, he will accomplish his object 

 more fully than by giving a general description of several 

 insects; and he proposes to notice '^?'s^, — and somewhat in detail, 

 so that it may be recognised, — the ijisect itself. 



The H. abietis belongs to the order Colcoptera (or Beetle order), 

 subclass Holometal)ola,oi the class of Inseda, following the usual 

 system of classification. It may be of interest, and perhaps use 

 to some, to explain the term Holometahola as applied to this sub- 

 class of insects. As the word indicates, it means " whole " or 

 *' complete change," and its application arises from the fact that 

 these insects pass through three complete changes of appearance 

 or metamorphoses from the tim-e the egg is deposited till the 

 insect appears perfectly developed : — Is^, On leaving the egg a 

 larva is produced, having a mouth suited for chewing; the body 

 is usually soft, in rings or segments, and provided with three 

 pairs of rudimentary legs ; in this stage a very common name for 

 it is that of " grub." 2d, The larva sooner or later (according to 

 the species) assumes a different form by passing into the chrysalis 

 state, and is termed a -puipa; it is usually covered with a some- 

 what tough skin or coat, and remains in a stationary condition. 

 Zd, The final change is reached when the perfect insect or imago 

 bursts its covering ; by this time it is provided with wings and 

 properly developed legs, and differs from its parents only in size. 



1. Description. — The body of a full-grown H. abietis is about half 

 an inch in length, and of a dull pitchy black colour, with 

 scattered yellow patches, which in reality are masses of closely 

 laid yellow hairs. It is divided into three distinct segments, viz. 

 — l^t, The head dotted over with patches of yellow hairs on a 



