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Injurious Insects


Order Coleoptera: beetles or shield-winged insects
Order Diptera: Two-winged insects
Order Hemiptera: The true bugs
Order Hyrnenoptera: bees, wasps, ants, flies
Order Lepidoptera: butterflies and moths
Insects exist in four different stages. First, the egg; second, the larva; third, the pupa or chrysalis; and fourth, the imago. The parent insect never makes mistakes in providing for posterity, but deposits her eggs on or in just the kind of food her young requires. With most insects the parents live upon a very different kind of food from that on which their numerous offspring feed, and this makes it seem all the more wonderful that they should know so well where to place their eggs. The eggs hatch sometimes within a few days, others take weeks, and some pass the winter months, and hatch with the warmth of the spring sun. It is noticable that those eggs that are not to be hatched until the following spring, are not attached to the leaves or other perishable part of a tree or shrub, but are securely glued to the bark of a twig or branch; they are, moreover, often covered with a kind of varnish which protects them from the rains.

Unlike other eggs, those of insects are not injured by intense cold. The young of all insects, of whatever class, are called larva (plural larvae, a Latin word meaning a mask - it being in this stage so unlike the perfect insect that its real form may be said to be masked).

Distinct names are popularly given to the larvae of different insects. The larvae of Butterflies and Moths are known as caterpillars; those of the Beetles are called grubs, and when they live in the wood of trees, etc., borers; the larvae of the two-winged flies are known as maggots. In a general way, larvae of most kinds are popularly called "worms," which, though incorrect, has for some insects, as has the term "bug" for others, been adopted by entomologists as the common name for the larvae of certain species - for example, "Army-worm," "Canker-worm," etc. The larva is the growing state of the insect, in which it feeds voraciously, moulting, or throwing off its skin from time to time until its full size is attained.

The larval stage may last but for a week or two, but in some insects is known to extend over several years. In some insects, as the Mosquitoes and Dragon Flies, the life of the larva is passed entirely in the water. When the larva has made its full growth it passes into the state of the pupa - (the name for an infant rolled up in bandages after the manner of the ancient Romans), this is also called chrysalis, from the Greek word for gold, as some have gold-like markings. Most insects are in this state perfectly dormant, while a few, as will be noticed further on, remain active. Some in their last moult appear as if swathed in a hard mummy-like case, others make a cocoon of silken threads, like the Silk-worm, in which to assume this state; some make a hollow chamber in the earth for the same purpose; and a number draw together leaves to form a covering to hide them while in the pupa state. The insect may remain in the pupa state for a few days or weeks, or it may pass the winter in this dormant condition. The methods by which the escape from this imprisonment is made at the proper time, are various and interesting to the observer. In due time it comes forth, and when, as in the case of some moths, it has spread and dried its wings, it seems wonderful that it could have been packed in so small a space.

The perfect insect which is usually provided with wings, is also called the Imago, the Latin for an appearance or an image. In the study of insects, it is convenient to bring them together in what are termed Orders, according to their general resemblances. There are seven of these Orders, each of which is subdivided into families, genera, etc.