Chap. 80.] VARIETIES OF THE TEREDO. 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 37 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 lias been cut 

 around. 38 It is said that the larch, when used for sea-going 

 ships, is liable to the attacks 39 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 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 teetli : 

 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. 40 "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, 41 will 

 never spoil in water. The followers of Alexander the Great 

 have left a statement that, at Tylos, an island in the Red Sea, 



37 A variety of the oak. See c. 6 of this Book. 



38 As mentioned at the end of c. 74. 39 See B. xi. c. 2. 

 40 See B. xvii. c. 37. 41 In c. 74. 



