Chap. 80.] 
VAEIETIES or THE TEEEDO. 
425 
under ground : the same is the case, also, with the juniper ; 
which is equally serviceable when exposed to the atmosphere. 
The woods of the beech and the cerrus^' very quickly dete- 
riorate, and that of the sesculus will not withstand the action 
of water. On the other hand, the alder, when driven into the 
ground in marshy localities, is of everlasting duration, and 
able to support the very heaviest weights. The wood of the 
cherry is strong, while those of the elm and the ash are pli- 
able, though apt to warp : these last will still retain their 
flexibility, and be less liable to warp, if the wood is left to 
stand and dry upon the trunk after the pith has been cut 
around.^^ It is said that the larch, when used for sea- going 
ships, is liable to the attacks^^ of the teredo, as, in fact, all the 
woods are, with the exception of the wild and cultivated olive. 
It is a fact, too, that there are some woods that are more liable 
to spoil in the sea, and others in the ground. 
CHAP. 80. (41.) VARIETIES OF THE TEEEDO. 
There are four kinds of insects that attack wood. Tlie 
teredo has a head remarkably large in proportion to the other 
part of the body, and gnaws away the wood with its teeth : 
its attacks, however, are confined solely to the sea, and it is 
generally thought that this is the only insect that is properly 
so called. The wood- worm that prevails on the land is known 
as the tinea,'' while those which resemble a gnat in appear- 
ance are called thripes." The fourth kind of wood- worm 
belongs to the maggot class ; some of them being engendered 
by the corruption of the juices of the wood itself, and others 
being produced, just as in the trees, by the worm known as 
the cerastes. When this worm has eaten away enough of 
the wood to enable it to turn round, it gives birth to another. 
The generation of these insects is prevented, however, by the 
bitterness that exists in some woods, the cypress, and the 
hardness of others, the box, for instance. 
It is said, too, that the fir, if barked about the time of bud- 
ding, and at the period of the moon already mentioned,*^ will 
never spoil in water. The followers of Alexander the Great 
have left a statement that, at Tylos, an island in the Eed Sea, 
37 A variety of the oak. See c. 6 of this Book. 
3^ As mentioned at the end of c. 74. 29 g^e B. xi. c. 2. 
See B. xvii. c. 37. In c. 74. 
