THE ELM. 115 



and diseased from some other cause, and which incipient 

 decay renders the inner bark of the tree an appropriate 

 food for the larva of the beetle. It is, however, the 

 opinion of Mr. Spence, and other eminent entomologists, 

 that when the Scolyti are very numerous, the perforations 

 made by the perfect insects in healthy trees for the sake 

 of food only, are apt to bring on that incipient decay 

 or carcinoma which soon reduces the tree to a fit state 

 for the reception of the eggs and larvae. If such indeed 

 be the case, we strongly recommend the preventive mea- 

 sures suggested by M. Audouin, the substance of which 

 will be found in Loudon's " Arboretum Britannicum," 

 where a figure of the insect, and other interesting 

 particulars respecting its habits, are given. The 

 foliage of the Elm is also often much injured, in some 

 years completely destroyed, by the larva? of another coleo- 

 pterous insect belonging to the genus Galleruca, to which 

 we may add the Elm flea, a pretty species of Haltica, 

 which feeds upon the leaves in its perfect as well as in 

 its larva state. Amongst its lepidopterous assailants are 

 the PortJiesia clirysorrlicea and occasionally the Cossus I'lgni- 

 perda, the Imago, Pupa, and caterpillar of which fine 

 insect are already beautifully figured in the " Arboretum 

 Britannicum." It is also sometimes subject to an ulcer- 

 ous sort of disease produced by an extravasation of the sap 

 or cambium, and causing the discharge of a thick sweetish 

 fluid ; for this no effective remedy has yet been discovered. 



Among the varieties which, from their general aspect 

 and habit, may safely be referred to the common Elm, 

 the following are the principal that attain a timber-like 

 size. 



U. c. vulgaris, more irregular in its growth than the 

 typical form, the branches are nearly horizontal in exposed 



