Damselfly

They are the two branches of the order Odonata. A damselfly, suborder Zygoptera, is slender and delicate, a weak fluttering flier that usually rests with its wings folded together along or above the body, and it has small eyes set well apart on the sides of a wide head, with fore and hind wings of similar narrow shape. A dragonfly, suborder Anisoptera, is stouter and a powerful flier that rests with its wings held out flat, and it has large eyes that meet or nearly meet on top of the head, with broad hind wings. In short, a fine, drifting insect that folds its wings when it lands is a damselfly, and a robust, fast one that keeps its wings spread is a dragonfly.

The larva, sometimes called a nymph, lives underwater for several months to a year or more, usually clambering slowly through submerged plants and leaf litter and ambushing small prey with a hinged, extendable lower jaw that shoots out to grab it. It breathes through three flat, leaf-shaped structures at the tip of its abdomen, which are packed with fine tubes and blood vessels and take up oxygen from the water. These gills double as swimming paddles, letting the larva scull backwards in short bursts, and if a predator seizes one, the larva can shed it at a weak point and swim off, later regrowing a replacement.

The shape comes from the unusual way odonates mate. The male's genital opening is near the tip of his abdomen, but his mating organ is under the front of it, so before mating he transfers sperm forward to that organ. He then grasps the female by the neck or head with claspers at the end of his abdomen, and she bends her abdomen forward and up to bring her genital opening against his mating organ under his thorax. The two bodies together make a rough heart or closed wheel. In many damselflies the male's organ is also shaped to rake out sperm from previous males before he adds his own, so the position serves sperm competition as well as mating.

Generally yes. Damselfly larvae need reasonably clean, well-oxygenated water and a good structure of submerged and marginal plants to hunt and hide among, and different species have different tolerances, so the range of damselflies breeding at a pond is a useful rough guide to its condition. A pond that attracts several species and where you can find larvae and see newly emerged adults drying their wings on stems is in good shape. To encourage them, a garden pond should have gently sloping edges, plenty of native water and marginal plants, some open water, a sunny position, and no fish, which eat the larvae.