seriously affect the useful life of wood are the shipworms (teredos) of the 

 family Teredinidae and small (2 millimeters] crustaceans of the genus 

 Limnoria. These marine biota are generally more active in clean water with 

 high dissolved oxygen. On land, the most destructive insects are termites. 

 Also on land but more in air, and very destructive in the presence of 

 moisture or intermittent wetting are the fungi and bacteria. Preservative 

 treatment can reduce the destructive effects of the various biota and 

 extend the useful life of wood but cannot completely prevent the attacks. 

 Cracks or holes in the wood or leaching of the preservatives will eventually 

 allow access for some marine borer or nest of termites. 



b. Teredinidae . These are marine bivalve mollusks that have evolved 

 into a long wormlike shape with its "shell" parts having become a set of 

 grinders at one end that the teredo uses to bore holes in wood. An adult 

 can be 50 to 100 millimeters long and 5 to 10 millimeters in diameter (Fig. 

 62). The individual enters the wood as a larva by making a small hole 

 that is never enlarged at the surface. As it grows, the teredo bores a 

 larger hole into the wood at the rate of 20 to 300 millimeters per month to 

 accommodate its whole body and apparently to feed itself (Fig. 63). An 

 infestation of teredos can destroy an untreated pile at the mud line in 5 

 to 6 months (Kofoid and Miller, 1927). Species found in abundance in U.S. 

 waters are Teredo diegensis and Teredo navalis. Teredos are sensitive to 

 coal tar creosote treatment. 



c. Limnoria. These are small marine crustaceans about 2 millimeters 

 long and less than 1 millimeter wide (Fig. 64) that either enter the wood 

 in the adult stage or are hatched and remain in the same piece of wood. 

 They use the wood as habitat and apparently as food supply because they 

 continue to bore holes after they are securely entrenched in the wood (Ray, 

 1959). They bore at the rate of about 0.5 millimeter per day (Kofoid and 

 Miller, 1927). At this rate, a heavy infestation of limnoria could eat 

 through a 30-centimeter untreated pile in about a year. One species, 

 Limnoria tripunctata, is present off most of the U.S. coastline (see Fig. 

 65). A subspecies, Tripunctata mengies is found all along the Atlantic 

 seaboard and in the Pacific Ocean from the southern end of the South Island 

 of New Zealand to several hundred miles north of Vancouver, Canada. Limnoria 

 tripunctata is particularly troublesome because it apparently is not repelled 

 by coal tar creosote preservative (American Society for Testing Materials, 

 1957). Where L. tripunctata is present the dual treatment, described in 

 paragraph 6, Preservative Treatment of Wood, is required. Figure 66 shows 

 the damage that can occur from limnoria attack. 



d. Termites. The principal termite species attacking wooden structures 

 in the United States is a subterranean type named Reticulitermes hesperus. 

 The typical life cycle of this species starts with winged reproductive 

 adults that fly from the nest for the purpose of establishing new colonies. 

 When a pair finds a suitable environment they start a colony. In 5 or 6 

 years, a colony may contain several thousand individuals (Palermo, 1951). 



Termites are antlike insects about 5 millimeters long that spend their 

 lives inside an earth nest or gnawing tubes through available wood (except 

 for the winged adults) . Termite damage is not evident to casual observation 

 because the outer layer of wood is left untouched for their own protection. 

 The usual evidence of their presence are the piles of fecal pellets that 



246 



