ri4 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



17. Some Observations on the Entomology of the 

 Scots Pine. 



{With Two Plates.) 

 By James W. Munro, B.Sc. 



During the past four years, the writer has had many oppor- 

 tunities of studying insect Hfe in the forest, and especially in 

 our Scots pine woods. In view of the comparatively small 

 attention paid to forest insects and their depredations in our 

 woodlands in this country, and especially as the literature con- 

 cerning them is scattered, and is in fact largely German, it is 

 thought that the following notes and observations may be of 

 interest. In the present paper these are confined to the insect 

 enemies of the Scots pine, and among them to the Coleoptera or 

 Beetles. 



Of all our Scottish timber trees the Scots pine probably 

 supports the largest number of insects. This is not surprising 

 when we consider that it has been for long years the chief timber 

 tree. It is, moreover, an indigenous species, a fact which is 

 itself sufficient to account for its being the host of a considerable 

 number of insects. Of the Coleoptera alone it supports twenty 

 species belonging to eleven genera. Four families are repre- 

 sented — Cerambycidae, Anobiid?e, Curculionidae, and Scolyti- 

 dae, i.e. longicorns, woodborers, weevils, and bark beetles. 

 Many of these beetles are to be found only on the Scots pine, 

 and others of them prefer it to their other hosts such as 

 spruce. 



In the following account only those species which are of 

 economic importance, or which, under favourable conditions, 

 may be expected to prove of economic importance, have been 

 considered. This reduces the number of families under con- 

 sideration to two, namely, Scolytidae and Curculionida?, the bark 

 beetles and the weevils. 



The Scolytidae attacking Scots pine are comprised in the 

 two tribes, Hylesinina and Dryocaetina. The representatives of 

 these tribes differ in one easily recognisable feature. In the 

 HylesininaC the head is not covered by the pro-thorax when the 

 beetles are viewed from above. In the Dryocaetina the head is 

 so sunk in the pro-thorax as to be completely hidden by it. 

 These characters are readily seen in Alyelophilus piniperda and 



