CAUSES OF DECAY AND DESTRUCTION OF TIMBER 265 



The Limnoria Terebrans, sometimes called the " boring 

 gribble," and in Australia the " cobra," is always found in 

 large numbers together, and in most parts of the world. 

 It is only about the size of a grain of rice, in colour light 

 grey, and very similar to the softer woods which it frequents; 

 the only conspicuous points of the animal are the two black 

 eyes. It can swim, crawl, and jump. 



The limnoria differs from the teredo, as it devours the 

 wood and its tunnel forms both food and shelter. It 

 attacks the wood by means of its mandibles or claws, and 

 makes a very clear cut excavation. It works on the 

 surface of timber so that its destructive work can be 

 plainly seen, and when the wood is bored all over to the 

 depth of perhaps half an inch it becomes brittle and is 

 washed away by the movement of the water, thus affording 

 fresh wood for the animal to act upon. The tunnels are 

 only about half an inch in length, slightly longer than the 

 animal itself, and are beautifully formed ; like those of the 

 teredo, they are usually parallel with the grain of the wood 

 (see Fig. 36). The multitude of these animals compensates 

 for their small size. Not long ago, when examining the 

 work of this creature on a piece of wood 10 inches square 

 by 3 inches thick, the author placed it in a pail of salt 

 water with the intention of keeping up life, but without 

 success ; hundreds of these animals came out of the wood, 

 and the water looked just as though a couple of handfuls of 

 rice had been thrown in. The limnoria often works in 

 conjunction with the teredo, but it also infests the waters 

 of colder seas where the teredo cannot exist, and has thus a 

 wider range. It attacks most kinds of wood, even light 

 scantlings of greenheart after a time, but prefers soft woods, 

 and will eat pitch pine at the rate of half an inch a year on 

 the northern coasts of Britain. Like the teredo, it also 

 works from about half-tide level down to the ground, and is 



