CHAP. 80. (41.)—VARIETIES OF THE TEREDO.
There are four kinds of insects that attack wood. The
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 appearance 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
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 budding, and at the period of the moon already mentioned,2
never spoil in water. The followers of Alexander the Great
have left a statement that, at Tylos, an island in the Red Sea,
there are trees, of which ships are built, the wood of which
has been found uninjured at the end of two hundred years,3
even if it has been under water all that time. They say, also,
that in the same island there is a certain shrub,4
thickness of a walking-stick only, and spotted like a tiger's
skin: it is very heavy, and will break like glass if it happens
to fall upon a hard substance.