Miscellaneous. 451 



MISCELLANEOUS. 



What is the best plan to be adopted for the destruction of the Cossus 

 ligniperda and Scolytus destructor ? By C. J. Cox, M.D.* 



Every person at all conversant with merely an outline of gardening, 

 must be perfectly aware how seriously trees are sometimes wounded, 

 and yet perfectly recover, but that the presence of a few obnoxious 

 insects, on the least derangement of the soil, inimical to its habits, 

 very speedily causes it to languish, sicken, and die ; from the ac- 

 curate knowledge we possess of the habits of these insects, and from 

 the fact that a tree suffers comparatively nothing from a wound, we 

 have carried out, with most perfect success, the following method of 

 treatment to remove or destroy the larvee of the Cossus. 



Having ascertained that a tree is infested by these insects, and 

 knowing by their habits that they are sure to be more or less about 

 its base, we ought immediately to commence by removing the soil 

 from around it to the depth of at least a foot, scraping off all the old 

 and decayed bark above and below ; numerous perforations will appear 

 on its removal, these ought to be carefully examined — their character, 

 as regards size, colour, or depth ; if small and fresh, the insect is 

 only a short distance in ; it may be destroyed or extracted by inserting 

 a piece of wire ; if the channel winds so that the wire cannot reach 

 it, it must be followed until the larva is killed, as the incision into 

 the stem is of less danger than the corrosion of the insect ; having 

 cleaned the wounds well by removing all refuse matter, a compost 

 of clay and cow manure ought to be inserted. The tree requires 

 watching for a week or fortnight to see if any yet remain ; their 

 exuviae protruding from their channels being sure to lead to their 

 detection. To destroy the ova and very young larvae, yet in the 

 crevices of the bark, treat the same as for the Scolytus. 



To destroy the Scolytus, remove all the old infected bark ; the 

 entrance to the parent tubes is then exposed ; as soon as we find the 

 parent channel, and knowing it always proceeds directly upwards, 

 and is always superficial, we must, with the angle of the scraper, cut 

 out a small piece of bark ; the lateral tubes are thus destroyed with 

 the young larvae ; the tree must afterwards be washed with a strong 

 solution of lime-water, coloured by soot ; the tree ought to be 

 watched for a fortnight. Should any of the parent insects have 

 escaped, the exuvial dust falling from their tubes on the stem will 

 lead to their detection. 



By carrying out this plan in our gardens, we have saved the re- 

 mainder of our ornamental elm-trees ; and when we consider that 

 one man can partially bark eight or ten trees in the day, by means 

 of a double-handled scraper, similar to that used by coopers, it has 

 been a most inexpensive process ; thus, instead of gazing on a blighted 

 foliage and stag- horned trunk, the withered and sickly tinge has 

 given place to a most luxurious green and healthy appearance. 



* From a paper read before the Royal Botanical Society of London, 

 Aug, 10, 1848. 



30* .JDaubI 



