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CONTENTS.

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INSECTS

INJURIOUS TO VEGETATION.

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INTRODUCTION.

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INSECT DEFINED. - BRAIN AND NERVES. - AIR-PIPES AND BREATHING-HOLES.

HEART AND BLOOD. — INSECTS ARE PRODUCED FROM Eggs. - METAMORPHOSES, OR TRANSFORMATIONS. — EXAMPLES OF COMPLETE TRANSFORMATION. — PARTIAL TRANSFORMATION. — Larva, OR INFANT State. — PUPA, OR INTERMEDIATE State. -- ADULT, OR WINGED State. — HEAD, EYES, ANTENNÆ, AND MOUTH. - THORAX OR CHEST, WINGS, AND Legs. — ABDOMEN OR HIND-BODY, PIERCER, AND STING.– NUMBER OF INSECTS COMPARED WITH PLANTS. - CLASSIFICATION. ORDERS. COLEOPTERA. ORTHOPTERA. HEMIPTERA. NEUROPTERA. LEPIDOPTERA. HYMENOPTERA. DIPTERA. OTHER ORDERS AND GROUPS. - REMARKS ON SCIENTIFIC NAMES.

The benefits which we derive from insects, though neither few in number nor inconsiderable in amount, are, if we except those of the silk-worm, the bee, and the cochenille, not very obvious, and are almost entirely beyond our influence. On the contrary, the injuries that we suffer from them are becoming yearly more apparent, and are more or less within our control. A familiar acquaintance with our insect enemies and friends, in all their forms and disguises, will afford us much help in the discovery and proper application of the remedies for the depredations of the former, and will tend to remove the repugnance wherewith the latter are commonly regarded.

Destructive insects have their appointed tasks, and are limited in the performance of them; they are exposed to many accidents through the influence of the elements, and they fall a prey to numerous animals, many of them also of the insect race, which, while they fulfil their own part in the economy of nature, contribute to prevent the undue increase of the noxious tribes. Too often, by an unwise interference with the plan of Providence, we defeat the very measures contrived for our protection. We not only suffer from our own carelessness, but through ignorance fall into many mistakes. Civilization and cultivation, in many cases, have destroyed the balance originally existing between plants and insects, and between the latter and other animals. Deprived of their natural food by the removal of the forest-trees and shrubs, and the other indigenous plants that once covered the soil, insects have now no other resource than the cultivated plants that have taken the place of the original vegetation. The destruction of insecteating animals, whether quadrupeds, birds, or reptiles, has doubtless tended greatly to the increase of insects. Colonization and commerce have, to some extent, introduced foreign insects into countries where they were before unknown. It is to such causes as these, that we are to attribute the unwelcome appearance and the undue multiplication of many insects in our cultivated grounds, and even in our store-houses and dwellings. We have no reason to believe that any absolutely new insects are generated or created from time to time. The supposed new species, made known to us first by their unwonted depredations, may have come to us from other parts, or may have been driven by the hand of improvement from their native haunts, where heretofore the race had lived in obscurity, and thus had escaped the notice of man.

To understand the relations that insects bear to each other and to other objects, and to learn how best to check the ravages of the noxious tribes, we must make ourselves thoroughly acquainted with the natural history of these animals. This subject is particularly important to all persons who are interested in agricultural pursuits. For their use, chiefly, this account of the principal insects that are injurious to vegetation in New England, has been prepared. It has been thought best to prefix thereto some remarks on the structure and classification of insects, to serve as an introduction to the succeeding chapters, and, in some measure, to supply the want of a more general and complete work on this branch of natural history.

The word Insect, which, in the Latin language, from whence it was derived, means cut into or notched, was designed to express one of the chief characters of this group of animals, whose body is marked by several cross-lines or incisions. The parts between these cross-lines are called segments, or rings, and consist of a number of jointed pieces, more or less movable on each other.

Insects have a very small brain, and, instead of a spinal marrow, a kind of knotted cord, extending from the brain to the hinder extremity; and numerous small whitish threads, which are the nerves, spread from the brain and knots, in various directions. Two long air-pipes, within their bodies, together with an immense number of smaller pipes, supply the want of lungs, and carry the air to every part. Insects do not breathe through their mouths, but through little holes, called spiracles, generally nine in number, along each side of the body. Some, however, have the breathing-holes placed in the hinder extremity, and a few young water-insects breathe by means of gills. The heart is a long tube, lying under the skin of the back, having little holes on each side for the admission of the juices of the body, which are prevented from escaping again by valves or clappers, formed to close the holes within. Moreover, this tubular heart is divided into several chambers, by transverse partitions, in each of which there is a hole shut by a valve, which allows the blood to flow only from the hinder to the fore part of the heart, and prevents it from passing in the contrary direction. The blood, which is a colorless or yellowish fluid, does not circulate in proper arteries and veins; but is driven from the fore part of the heart into the head, and thence escapes into the body, where it is mingled with the nutritive juices that filter through the sides of the intestines, and the mingled fluid penetrates the crevices among the flesh and other internal parts, flowing along the sides of the airpipes, whereby it receives from the air that influence which renders it fitted to nourish the frame and maintain life.

Insects are never spontaneously generated from putrid animal or vegetable matter, but are produced from eggs. A few, such as some plant-lice, do not lay their eggs, but retain them within

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