Chap. 37.] 
THE DISEASES OE TEEES. 
519 
comparative amount of sap that they contain ; while some, 
again, are troubled with obesity, as in the case of all the re- 
sinous trees, which, when sufferirig from excessive fatness, anj 
changed into a torch-tree.^^ "When the roots, too, begin to 
wax fat, trees, like animals, are apt to perish from excess of 
fatness. Sometimes, too, a pestilence will prevail in certain 
classes of trees, just as among men, we see maladies attack, 
at one time the slave class, and at another the common people, 
in cities or in the country, as the case may be. 
Trees are more or less attacked by worms ; but still, nearly 
all are subject to them in some degree, and this the birds^"^ are 
able to detect by the hollow sound produced on tapping at 
the bark. These worms even have now begun to be looked 
upon as delicacies by epicures, and the large ones found in 
the robur are held in high esteem ; they are known to us by 
the name of cossis;'' and are even fed with meal, in order 
to fatten them ! But it is the pear, the apple, and the fig^* 
that are most subject to their attacks, the trees that are bitter 
and odoriferous enjoying a comparative exemption from them. 
Of those which infest the fig, some breed in the tree itself, 
while others, again, are produced by the worm known as the 
cerastes ; they all, however, equally assume the form of the 
cerastes,^^ and emit a small shrill noise. The service-tree is 
infested, too, with a red hairy worm, which kills it; and the 
medlar, when old, is subject to a similar malady. 
The disease known as sideration entirely depends upon the 
heavens ; and hence we may class under this head, the ill 
See B. xvi. c. 19. He alludes to an exuberant secretion of resin, in 
which case the tree becomes charged Avith it like a torch. 
He alludes to the epidemic and contagious maladies by which trees 
are attacked. The causes of these attacks are often unknown, but they 
may probably proceed, in many instances, from springs of hot water, or 
gaseous emanations secreted in the earth. 
82 The woodpecker more particularly. See B. x. c. 20. 
83 It is not known, with certainty, what these worms or caterpillars 
were. The larva of the Capricorn beetle, or of the stagrbeetle, has been 
suggested. Geoffroi thinks that it may have been the larva of the palm- 
weevil. This taste for caterpillars, probably, no longer prevails in auy 
part of Europe. 
8i This passage, which is quite conformable to truth, is from Theo- 
phrastus. Hist. Plant. B. iv. c. 16, and B. iii. c. 12. 
«5 See B. xvi. c. 80. 
