6i8 



The Elm Bark Beetle. 



[JAN, 



and the bark should be burned. Where the bark is very thin 

 it should be remembered that at such places the wood will 

 have been bored to a greater extent. If such badly infested 

 trees are allowed to stand they act as centres of infection. 

 According to the life history given above such felling and barking 

 should take place in late July or early in August, before the 

 issue of the brood. 



" Felled healthy elms should never be allowed to lie unbarked. 

 The Elm Bark Beetle lays very willingly in such felled trees, 

 hence a measure which is sometimes practised against the 

 Elm Bark Beetle in cases where many trees have not been 

 attacked, is to use such felled trees or thick branches as traps, 

 always taking care that the traps be visited and removed 

 before the beetles bred in them have become adult and have 

 issued. 



"2. The rough outer bark where the insects are known to 

 be at work should be shaved off by means of a spokeshave. 

 The foundation for this treatment arises from a practice in 

 France and elsewhere of paring off the outer bark of apple 

 trees that are bark bound in order that their vigour may 

 be restored. A French experimenter, M. Robert observed 

 (Gardeners' Chronicle, 1848) in connection with Scolytus larvae 

 that they failed to complete their development if they were 

 not protected from the drying influence of the air, or if their 

 burrows overflowed with sap. These observations led him to 

 practice against the Elm Bark Beetle, the ' removal of all the 

 superficial portion of the bark, i.e., all the corky portion.' 

 The grubs in the trees so treated perished, and the new bark 

 was too thin for the adult beetles to choose it for egg-laying. 

 So satisfied was M. Robert that he extended his treatment, 

 and with justification, to more than 2,000 elms. 



"3. Young trees may be protected against the adult beetles 

 by smearing them with tar or cow-dung or lime. A smear 

 used in Germany for this purpose, known as Leinweher's 

 composition is made up as follows : — 5 lb. of tobacco mixed 

 with half a pailful of hot water and kept hot for 24 hours ; 

 the water squeezed out of the tobacco is mixed with half a 

 pailful of bullock's blood, one part of slaked lime and sixteen 

 parts of cow-dung. This is kept in an open tub, stirred once 

 a day and used after fermentation has set in to paint the 



