FAILURE OF WOOD BECAUSE OF ANIMAL LIFE, WOODBORERS.
The forms of animal life that attack woods may be divided according to their habits or environment into marine woodborers' and terrestrial woodborers.
The quantity of wood destroyed by marine woodborers is considerable, but the proportion is much smaller than it was when wood was used more extensively in marine constructions. The total value of wood destroyed by marine borers is much less than the total value of woods and living trees destroyed by terrestrial borers.
The harm done by these borers has not always been measur able by direct costs, since it is recorded that owners of wooden ships once discriminated against harbors in which numbers of these pests were known to be present.
Most perforations found in timbers that have been in sea water are attributed to the Teredo navalis, probably because this shipworm was one of the first to be studied and was the one selected for description in some of the earlier text-books. The Teredo navalis is worthy of the attention it receives, but it must not be forgotten that there are other marine woodborers.