868 THE ENTOMOLOGIST. 



his account of its economy is the first we have. Ratzebourg 

 has, however, given us a much more complete Hfe-history in 

 his ' Forst-Insecten Kafer,' in which work he has figured the 

 insect in all its stages. It has sometimes been most abundant 

 in the dockyards of France, perforating the oak-timber and 

 reducing it to powder. It has been found that in all stages 

 this pest can be destroyed by immersing the timber in water. 

 In the oak forests of Northern Europe it abounds ; but in 

 England it is go great a rarity, that a single specimen, taken 

 in Windsor Forest, was esteemed a great treasure. The 

 second insect is a marine wood-louse of very small size, but 

 of great destructive powers : its food consists exclusively of 

 timber, for, on examining the contents of its stomach, these 

 have been found to consist entirely of comminuted wood. 

 Unlike Lymexylon, which is killed by immersion in water, 

 Limnoria only feeds on timber that is either partially or 

 entirely submerged. Mr. Coldstream has collected a vast 

 number of facts respecting this creature, and has published 

 them in the 'Edinburgh New Philosophical Journal' for 

 1834. From this it appears that it commences its ravages on 

 a piece of wood by excavating the soft parts, leaving those 

 harder parts which mark the boundaries of annual growth, 

 and subsequently attacks these, the portion consumed being 

 under water, or, at any rate, below high-water mark. During 

 the building of the Bell-Rock lighthouse it was necessary to 

 erect a temporary wooden building, in which the engineer 

 and his assistants resided, and which was supported by 

 twelve large beams of Memel fir, fixed in bolt-holes cut 

 in the rock ; the sides of these beams were charred and 

 pitched, but the bottoms, which closely fitted to the holes, 

 were left naked. In the second year the edges of these 

 timbers were in a state of decay, owing to the borings of the 

 Limnoria. The logs of Norwegian pine, laid down to support 

 the temporary tramroads, were greatly injured ; the timbers 

 at first ten inches square, in four years were reduced to 

 seven inches, thus losing at the rate of nearly an inch a year. 

 In some instances the house timbers were so completely eaten 

 away at the bottom that they stood clear of the rock, 

 supported only by the bolts and stanchions. The piles 

 supporting the timber-bridge at Montrose were so destroyed 

 by the boring of the Limnoria that the whole structure was 



