Amongst the insects which infest books in India are two genera, which are usually regarded as accomplices in the work of destruction, but which, on the contrary, pursue and greedily feed on the larvm of the death-watch and the numerous acari, which are believed to be the chief depredators that prey upon books. One of these maligned genera is a tiny tailless scorpion (Chelifer), of which three species have been noticed in Ceylon,—the C. lib rorum, Temp., C. oblongum, Temp., and C. acar oides, Hermann, the last of which, it is believed, had been introduced from Europe in Dutch and Portuguese books. Another genus of book insects is the Lepisma, the fish insect genus, and called so by Fabricius from its fish - like scales, tiny silvery creatures, which feast on the acari and soft-bodied insects that infest books. There have only been two species described, viz. the L. niveo fasciatus and L. niger, Temp. ; it has six legs. As insects are very destructive to books in India, and the pastes or gums employed in the bindings form special objects for the attacks of certain tribes, it may be useful to know that insects refuse to attack the gum of the cashew-nut fruit.
Mother insects deposit their eggs in localities suitable for their reception and future develop ment, selecting the object or substance to which instinct directed them as being the best adapted to serve those ends. Water for a few, and the soil of the earth for very many, but the vege table kingdom for vastly the greatest number, serve insects as suitable habitations for rearing their young. It is while in the state of larvm that they consume the greatest amount of food. Those living in the interior of timber or on vege tables, or other hard substances requiring mandu cation, are furnished with a pair of powerful mandibles or jaws, and another and less powerful pair of masticatory jaws or maxillae. Those which chiefly inhabit water are of carnivorous habits, and prey upon insects smaller and softer than themselves, are furnished similarly with jaws, but adapted for seizing and destroying their prey. Such as inhabit the soil are either vegetable feeders, and conform in their structure to that section, or are carnivorous, and are hence provided with the means of obtaining their food similar to those which inhabit the water. A few have auctorial mouths, but these feed upon the juices of animal and vegetable substances, especially when such are in a state of decomposition.
The lame of butterflies and moths are known as caterpillars. They remain in the larva state for very varied periods ; some for a brief time, others for a fortnight, a month, or several months, and in the larger Coleoptera from three to four years. During this period they are solely occupied
in eating, and their voracity is immense. After passing through the pupa state, the perfect insects come forth. They can walk and fly, but have not the same voracious appetite, and do not use the same food as in the larva state. Such is the case with all butterflies and moths, but not with all beetles. Grasshoppers and dragon-flies form a general exception, for they are as voracious and as capable of devouring much food in their perfect state as they were when in the larva condition.
The locust tribe, as defined by Westwood, includes all the grasshoppers, the females of which are destitute of an exserted ovipositor, and which have the antennae short, filiform, and with twenty or thirty joints. Locusts, at intervals of years, appear in myriads in Central and Southern Asia, Persia, and in Northern India, often after droughts, and eating up every green thing. When their larva are advancing along the ground, it is customary in some parts of Northern India to dig a trench in front of the advancing army, and as they tumble in, earth is shovelled in over them.
In Burma, where caterpillars appear at intervals in the paddy fields in immense numbers, devouring plants down to the roots, grass as well as paddy, moving on daily a few miles, the plan adopted in Hindustan could be usefully applied.
The itch insect (Acarus, sp.) and other para sites are a plague to man. See Louse.
(Estrus equi, of the south of Europe and Persia, is a dipterous insect. Its eggs are deposited on the hair of the horse, and licked into the stomach, and when complete, the insects pass through the canal.
Cephalmmia ovis (syn. Estrus ovis), of Europe and the E. Indies, lays its eggs in the nostrils of the sheep, and the worm from it occupies the frontal sinuses, and gives rise to fatal diseases.
Weevils and their allies are in immense num bers, and many species are of extreme beauty, but occasion much loss by their attacks on the cereal grains.
The scarlet mite, Acarus telarius, called also red spider, envelopes the leaves of a plant in a delicately woven web, which so checks the respira tion that the plant becomes dry and withered.
The insects in India which are the most de structive to living and dead vegetable substances belong to five families of Coleoptera, or beetles ; to two families of Hemiptera, or bugs ; to one of the Neuroptera, or lace wings; and to three of the Hymenoptera.