ORTHOPTERA. 



J 75 



trunks and branches of trees, or in timber. They line the galleries they make, which 

 are often so close together as to be separated only by a thin wall, the wood in the 

 interior being almost all eaten away. A few make openings to the exterior, and form 

 nests around the branches of trees ; these nests being sometimes as large as a sugar- 

 barrel, though the size varies considerably. The nests of most species are usually 

 placed entirely below the level of the ground, and often lie beneath mounds of 

 earth raised above the surface. Some of the larger African species, such as Termes 

 hcllicosus, build mounds of earth, frequently reaching a height of 12 or 14 feet. 

 These mounds, which may stand singly, or in groups of varying size, are divided 

 inside into chambers and galleries communicating with one another and with the 

 nests and galleries underground. The nests of this kind, which consist almost 

 entirely of clay, become in time quite hard and solid, and are much more 

 durable than those which are composed of particles of dead wood pasted 

 together with sticky saliva or with excrementitious matter. From the central 

 nests termites construct underground galleries or tunnels leading in different 

 directions, and sometimes reaching hundreds of feet in length. When it is 

 necessary for the workers to go above ground in search of food, they protect 

 themselves by building covered ways leading to the object they desire. Their 

 tunnels sometimes lead to the interior of houses, and when once termites gain 

 admittance in this way there is scarcely any limit to the mischief which may 

 result from their operations. The wooden pillars that support the roof, the wood- 

 work of the roof itself, and even articles of furniture, may be destroyed before 

 the inhabitants become aware of what is taking place. For in tunnelling through 

 wood termites take care to leave the outer shell intact ; and what appears on the 

 outside to be a solid piece of wood may consist in the interior of nothing but a 

 series of galleries lined with white-ant mortar. These insects easily make their 

 way into wooden boxes, and quickly destroy the books, papers, clothing, or what- 

 ever else they may contain. The rapidity with which they work is remarkable, 

 and in a single night they have been known to burrow up through the leg of a table, 

 then across the table, stopping on the way to devour the articles lying on it, and 

 down through another leg into the floor again. Forest trees, also, are often ruined 

 by the action of termites, which, in order to get at the dead branches will some- 

 times bore their way up through the trunk, and thus bring about its premature 

 decay. 



The book-lice and the other insects classed with them in the 

 family Psocidtv form another small group of Pseudoneuroptera. 

 They are mostly very small insects, with a proportionately big head, swollen in 

 front, and carrying prominent eyes, three ocelli, and bristle-like antenna'. Their 

 mandibles are horny at the tip, but the other parts of the mouth are usually soft 

 and membranous; the maxillae being bilobed, with four-jointed palpi, and the 

 palps of the bifid labium rudimentary. The middle segment of the thorax is 

 the largest, and the prothorax is usually very short and narrow. The wings, 

 which are wanting in some species, are slanting in repose, like the sides of a roof, 

 and cover over the abdomen : they are of an almost glassy transparency, and have 

 as a rule, an open system of neuration. The tarsi are composed of two or three 

 joints. Most species of Psocidce live in the open air, and feed on fungi, lichens, 



