FOREST INSECTS ON THE CULBIN SANDS. 1 37 



and probably formed part of the original fauna of Rothie- 

 murchus forest, for they are all recorded by Professor Hudson 

 Beare from the Nethy Bridge district. Three of them are of 

 special interest, namely, Ernobius nigrinus, Rhagiuvi indagatoTy 

 and Pityogenes guadridens. The first of these was the subject 

 of a note in the last part of these Transactions^ but some 

 account of the others may be of interest. 



R. tndagator, the Grey Rhagium, is, so far as I am aware, 

 restricted in its distribution to the North of Scotland, being 

 most common in the Dee valley, around Aboyne and up to 

 Ballochbuie, and around Forres, notably in Darnaway forest 

 and up to Rothiemurchus forest. It resembles in general 

 appearance the Common Rhagium, R. btfasdatum, but can easily 

 be recognised by its grey colour and dark markings. Its 

 habits differ from those of the Common Rhagium, R. tndagator 

 being chiefly a bark feeder while R. bifasciatum tunnels in 

 decaying or half-decayed wood. The Common Rhagium 

 pupates in the wood, the Grey Rhagium constructs a nest of 

 wood fibres resembling a half-finished cocoon, attached to the 

 inner side of the bark or in some cases to the wood of the stump 

 or log. 



Pityogenes quadridens like R. indagaior is a northern insect. 

 It occurs around Dunkeld, in the Dee valley (where it is 

 associated with Myelophilus mifwr) and in Darnaway forest. 

 It is slightly smaller than the common P. bidentatus, and the 

 males of the two species can be distinguished by the presence 

 in quadridens of an additional tooth on the apex of the wing-cover. 



The presence of E. fiigrinus, R. indagator, and P. quadridens 

 in the Culbin Sands fauna seems to me to indicate that that 

 fauna has been derived from the neighbouring woodlands of 

 Brodie and Darnaway, which in their turn had been invaded by 

 descendants of the fauna of the ancient forest of Rothiemurchus. 

 Another member of the Rothiemurchus fauna is represented 

 on the Sands by the Crested Titmouse (Parus cristatus), a bird 

 which is rare in Britain and is confined to our northern forests. 

 Curiously enough I observed it in company with the Blue-tit 

 busily exposing the galleries of Pityogenes quadridens in the 

 burned belt of pine adjoining the " Snab " nursery. That this 

 pretty and useful bird should continue to extend its range is 

 much to be hoped for. 



1 Vol xxxvi. p. 113. 

 VOL. XXXVI. PART II. K 



