ELM-BAEK BEETLE. 219 



but the trees that were experimented on were cleared of the 

 maggots. The treatment was appHed on a large scale, and 

 the barked trees were found, after exammation by the Com- 

 missioners of the Institute at two different periods, to be in 

 more vigorous health than the neighbouring ones of which the 

 bark was untouched. More than two thousand Elms were 

 thus treated.* 



A somewhat similar process was tried by the Botanic 

 Society in 1842 on trees infested by the Scolijtus destructor in 

 the belt of Elms encircling their garden in Eegent's Park, 

 London ; " it consists in divesting the tree of its rough outer 

 bark, being careful at the infested parts to go deep enough to 

 destroy the young larvas, and dressing with the usual mixture 

 of lime and cow-dung." This operation was found very 

 successful, and details with illustrations were given in a 

 paper read in 1848 before the Botanic Society. 



Various kinds of mixtures or dressings have been recom- 

 mended to be applied directly to the bark, in order to keep off 

 beetle attack, and anything of this kind that would make the 

 surface unpleasant to the beetle would certainly be of use so 

 long as it was not of a nature to hurt the tree, and if 

 previously the very rugged bark was partially smoothed it 

 would make the application of whatever mixture might be 

 chosen easier and more thorough. 



Washing down the trunks of attacked trees has not been 

 suggested, but, looking at the dislike of the female beetle to 

 moisture in her burrow, it would be worth while, in the case 

 of single trees which it was an object to preserve, to drench 

 the bark daily from a garden-engine for a short time when 

 the beetles were seen (or known by the wood-dust thrown out) 

 to be at work forming burrows for egg-laying. Where a 

 stronger application was needed, some of the various kinds of 

 soft-soap wash with a little mineral oil added, or a small 

 quantity of Paris-green (see references in Index), could not 

 fail to be very deterrent, if they were thrown in solution suffi- 

 ciently thick to settle into and choke the crannies or deep 

 cracks especially chosen by the beetles as the points from 

 which to start their burrows. 



One of the most important considerations, in regard to 

 prevention of attack, is the removal of all centres of infesta- 

 tion from which the beetles might spread to the sound trees. 



The possibility of clearing away or treating infested stand- 

 ing trees or infested limbs depends, of course, on local 

 circumstances ; but whatever care is exercised in other ways, 

 it is very unlikely that much good will be done in lessening 



* The above account is abridged from the leading article in the ' Gardeners' 

 Chronicle and Agiicultural Gazette ' for April 29th, 1848. 



