194 A BOOK OF INSECTS 



their attacks to dead or dying trees, and thus act as 

 vegetable scavengers. In this respect the great family of 

 long-horn beetles (Cerambycidce) is especially serviceable. 

 We have only a few representatives in this country, but 

 in the tropics the species are very numerous. " Probably 

 no portion of the world " (writes the Rev. Canon Fowler) 

 " contains a larger number than the densely timbered 

 Amazon basin. In these great forests the Longicornia 

 play a very important part in the economy of nature. 

 As soon as a tree dies and begins to decay, their larva?, 

 which are very often of great size, attack it and bore it 

 through and through ; the work of boring from their large 

 galleries is then taken up by various smaller species of 

 wood-boring Coleoptera, and free access is thus given to 

 the rain and moisture, which soon reduce the trunks to a 

 pulp, and cause them not only to disappear, but to act as 

 manure to those trees that take their places." But for 

 the agency of these and other insects, the forests would 

 gradually become blocked up with dead timber ; for wood 

 is a most enduring form of organic matter, and offers 

 stubborn resistance to the ordinary processes of decay. 



Termites, or " white ants," are another important 

 group of wood-feeding insects. Their destructive habits 

 often clash with the interests of mankind ; but in Nature's 

 scheme their work is wholly beneficial. The larva? of 

 wood-wasps (Shicidce) also feed upon wood. The best 

 known species is the giant wood-wasp (Sirex gigas), 

 which is apt to alarm those who know nothing of its 

 character. The insect is not uncommon in the British 

 Islands, but it is much more abundant on the Continent. 

 The female has a very hornet-like aspect, and carries a 

 formidable ovipositor which is often mistaken for a sting. 

 But this instrument is a tool, not a weapon. By its use 

 the wood-wasp bores a hole through the bark of a sickly 



