When full grown the larvæ crawl up the stem of some aquatic plant out of the water, and after resting there for a longer or shorter time the skin splits open along the thoracic region, and the perfect insect by degrees struggles out of its investment, and when the wings are dried it starts off to continue the same scene of rapine which has characterised its subterranean existence.
The perfect insect may be seen hawking about for insects in the neighbourhood of pools in all fine weather during the summer and autumn months. In dull weather, however, they usually remain at rest on the leaves of plants and trees, etc. The eyes of Dragon Flies are most beautiful objects when viewed under the microscope; they are composed of a great number of facets or lenses. In one species of Dragon Fly as many as 10,000 of these facets have been counted in each of its eyes.
Besides these compound eyes most dragon flies have additional eyes, called Ocelli, which are situated on the top of the head; they are, however, quite simple.
It is commonly thought by persons who are not naturalists that dragon flies sting; such an erroneous idea we take the opportunity to correct.
Fig. 54.—Libellula Depressa.
The Ornoptera are divided into two principal families.
Family 1, Libellulinæ.—To this family belong all the great dragon flies, mostly thick-bodied insects. It is subdivided into four sub-families.
To the first sub-family, the Libellulidæ, many common and familiar dragon flies belong. The best known is what is vulgarly called the "Horse-stinger" (Libellula depressa), an insect about two inches long, with a rather depressed abdomen, which is yellowish-brown, with yellow spots on the sides in the female, and coated with a beautiful violet-blue powder in the male.
It may be seen almost everywhere, hawking for flies about rivers and ponds, during warm weather.