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X. — The Structure, Bionomics, and Forest Importance of Myelophilus minor 
Hart. By Walter Ritchie, B.Sc., B.Sc. (Agr.) ; Fullerton Scholar, University 
of Aberdeen ; Research Scholar, University of Edinburgh. Communicated by 
Dr R. Stewart MacDougall. (With Two Plates.) 
(Read January 22, 1917. MS. received March 31, 1917. Issued separately December 4, 1917.) 
The two beetles Myelophilus minor Hart, and Myelophilus piniperda Linn, 
belong to the family Scolytidse (the Ipidse of Hagedorn), of the series Rliynchophora 
or snouted beetles. • 
The genus Myelophilus Eichhoff has the following characters : (l) the biting 
edges of the maxillae are beset with spines, (2) third basal tarsal joint broadened 
out, (3) head with rostrum visible, (4) funiculus of antenna six-jointed, (5) club of 
antennae not quite round but somewhat pointed at the apex, (6) head and thorax 
with outstanding hairs, (7) front edge of thorax not depressed in the middle. 
The genus has four species, of which two are native of Britain, viz. Myelophilus 
piniperda ( Hylurgus of the British catalogue), well known throughout Britain 
to the forester, and often called by him the “Pruner” ; and Myelophilus minor , till 
now scarcely known at all in Britain, and described by Fowler * as very rare. 
In the Aboyne district of Aberdeenshire, however, I have found this species 
occurring in very large numbers over an area of fifteen square miles. Later in 
this paper I give reasons for the references to this beetle in our British literature 
being so scanty. 
To the forester these two species are of primary importance, as they prove very 
destructive to pine plantations in all stages of growth ; firstly, by their attacking 
and boring into the tender shoots of pines ; and secondly, by boring into pine stems 
for breeding purposes, the brood galleries in the bast and cambial regions ultimately 
causing the death of the trees. 
The aim of the present paper is to describe the life-history, habits, and important 
anatomical features of M. minor, contrasting them with those of M ■ piniperda, so 
that its presence may be more readily recognised and preventive and remedial 
measures based on its life-history may be undertaken. 
Description of the Two British Species of the Genus Myelophilus. 
The following is Fowler’s t description : — 
M. piniperda L. — Black or pitchy black, or black with the elytra dull red, often 
entirely testaceous, shining ; oblong, subcylindrical, clothed with a rather scanty 
* Fowler’s Goleoptera of the British Islands, vol. v, p. 420. f Ibid. 
TRANS. ROY. SOC. EDIN., VOL. LI1, PART I (NO. 10). 
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