192 THE GYPSY MOTH. 



vigorous health than the neighboring ones of which the bark was 

 untouched. More than two thousand elms were thus treated. 



This account is abridged from the leading article in the " Gar. 

 deuer's Chronicle and Agricultural Gazette" for April 29, 1848, 

 and the method is well worth trying in our public and private 

 parks. It is not expensive ; the principle on which it acts as 

 regards vegetable growth is a well-known one, and as regards 

 insect health it is also well known that a sudden flow of the sap 

 that they feed on, or a sudden increase of moisture around them, 

 is very productive of unhealthfulness or of fatal diarrhoea to 

 vegetable-feeding grubs. 



A somewhat similar process was tried by the Botanic Society, in 

 1842, on trees infested by the Scolytus destructor in the belt of 

 elms encircling their garden in the Regents' 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 larvae, 

 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.* 



No injury to trees which have been scraped in the course 

 of the work on the gypsy moth has been observed, although 

 this practice has been continued for three years and more than 

 nine thousand trees have been scraped. Apple trees and elm 

 trees treated in this way have shown an immediate increase 

 of foliage area and growth, presenting a marked contrast to 

 trees near by which have been left untreated. Whether a re- 

 action will set in in future years remains to be seen. As yet 

 no serious reactionary effect has been noted. Trees which 

 have been scraped have exhibited remarkable vigor in healing 

 wounds. In the gypsy-moth work large elms are frequently 

 met with which cannot be cleared of the moth without shav- 

 ing off their outer bark. This bark often overgrows small 

 cavities in the trunk in such a manner that hiding-places for 

 the moth are formed which it is impossible to discover until 

 the rougher portion of the outer bark has been removed. 

 While that is being done, it is not difficult to expose these 

 hiding-places and to destroy any form of the moth found 

 within. 



* Fifth report of the United States Entomological Commission, 1886-90, pages 31, 32. 



