255 



lopped; standing trees must be girdled. /. {T.) lineatus : Felled 

 trunks must be lopped, the bark being left entire ; the branches or 

 the crowns of standing trees must be removed. 



Fir. Cryphalus piceae : Felled trunks must be lopped ; standing 

 trees must be girdled. /. ( T.) curvidens : The branches of felled 

 trunks . must be left only in very exposed situations — trap-trunks 

 are seldom of use in sheltered positions ; standing trees in exposed 

 situations must be double-ringed. 



Pine. Hylastes ater : Felled trunks in protected places, with 

 strips of bark removed — especially on the lower side. H. palliaius : 

 Felled, lopped, trunks in protected situations ; standing trees without 

 crowns or lopped. Hylesinus piniperda : Felled trunks must be 

 lopped ; standing trunks must be girdled or double-ringed, but are 

 eftective only beneath the rings, which must therefore be placed as 

 high as possible. H. minor : Felled, lopped trunks ; standing trees 

 must be girdled or double-ringed and the crowns must be removed — 

 the infestation of standing trunks is uncertain and tardy. Ips {T.) 

 sexdentatus : Felled trunks, lopped in protected situations, and with 

 branches in exposed ones. /. ( T.) proximus : Felled trunks, lopped 

 in exposed situations, and with branches in protected ones ; double- 

 ringing and scarification is advisable, because every help to rapid drying 

 — except direct sunshine — is valuable ; felled trunks are more readily 

 infested than standing ones ; the latter must be double-ringed or 

 have their crowns removed. /. {T.) lineaUts : Same treatment of 

 the traps as in the case of spruce. 



Nagel (W.). Bekampfung von Anohium striatum, Oliv., mittels 

 Cyanwasserstoffgasen. [Combating A. striatum by means of 

 Hydrocyanic Acid Gas.] — Zeiischr. angew. Ent., Berlin, vii, no. 2, 

 February 1921, pp. 340-348. 



The Anobiid beetle, Anohium striatum, Oliv., is one of the most 

 dangerous pests of timber. The adults mate when the weather turns 

 warm, and the eggs are laid in wood in cracks or in old bore-holes. A 

 few weeks later the larvae begin to do damage, and this continues 

 through the summer. After hibernating, thej^ begin feeding again 

 in spring and pupate in early summer. The beetles emerge a fort- 

 night later. 



The remedial measures hitherto tried have failed owing to the 

 inability of the substances used to penetrate wood. Nor is the use of 

 hydrocyanic acid gas as practised in flour mills more successful, 

 because only a minimum amount of gas is able to penetrate. 

 Satisfactory results have been attained by placing infested articles 

 in a vacuum chamber, exhausting the air until a reading of 47 cm. 

 was reached, and then pumping in the gas until the vacuum 

 decreased to 45-45-5 cm. It was found that a strength of 3-4- 

 volumes of HCN. per 100 of space killed all stages with a minimum 

 exposure of 24 hours. Treated articles must then be left for some 

 hours in an open room or, better still, the traces of poisonous gas 

 may be extracted in the vacuum chamber. 



The various experiments are described ; one of these proved that 

 a vacuum, by itself, is not harmful to the larvae. 



