Validity of Pissodes validirostris as a Species. 65 



V. On the Validity of Pissodes validirostris (Schoenh.) as a 

 Species. By R Stewart MacDougall, M.A., D.Sc. 



(Read 20th April 1898.) 



Pissodes is a genus of beetles belonging to the section 

 Ehyncophora, or Weevils, whose characteristic is the posses- 

 sion of a rostrum or proboscis. 



Of the twenty or so species belonging to the genus, five 

 are well-known forest pests, injurious to coniferous trees,^ 

 viz., P. notatus, P. pirn, and P, piniphihcs, which attack trees 

 of the genus Pinus ; P. harcyniae, which attacks the spruce ; 

 and P. piceae, whose host-plant is the silver fir. The two 

 last are said not to be found in Britain. 



Pissodes notatus (Fabr.), the small brown or white-spotted 

 weevil, measures on an average a quarter of an inch. The 

 posterior angles of its wrinkled prothorax project sharply, 

 and its hinder edges show two sinuous excavations. Both 

 the upper and under surface of the beetle are powdered with 

 white scales. On the upper surface of the prothorax stand 

 four well-marked white points, and a fifth on the scutellum. 

 The elytra have two transverse bands of scales, one in front 

 and one behind their middle. The front one, which is non- 

 continuous at the suture, is yellowish on either side externally, 

 whitish internally. The hinder band has almost the same 

 coloration ; it is broader externally than internally, and is 

 continuous right across the elytra. 



The larva is a fleshy, wrinkled, legless grub, with a brown 

 scaly head, and strong gnawing jaws. 



P. notatus is injurious chiefly in the larval condition. The 

 female lays her eggs in holes, made by her proboscis, in the 

 bark. The larvae on hatching out tunnel upwards or down- 

 wards in the cambial region, a trail of brown bore-dust 

 remaining to map out the path of the larva. When full fed, 

 the grub gnaws out a hole in the outer layers of the wood, 

 and in this hollo wed-out bed, protected by a cover of sawdust 



1 A full account of the biology of these insects, with preventive and 

 remedial measures, will be found in my two papers : "The Genus Pissodes 

 audits Importance in Forestry," in the TraiisactioTis of the Royal Scottish 

 Arhoricultural Society, 1896; and "Ueber Biologic und Generation von 

 P. notatus" iu the Forstlich-naturwissenchaftlicfien Zeitschri/t, 1898. 

 VOL. XIV. E 



