ORTHOPTERA. 
'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 
bellicosus, 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 Psocidce 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 antennae. 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, 
