Damselflies are insects belonging to the order Odonata, which also contains dragonflies. Often dragonflies are mistaken for damselflies and vice versa, but damselflies have their own sub-order, Zygoptera ( meaning ‘paired wings’) and there are distinct differences between the two groups of insects.
Damselflies are generally smaller than dragonflies, and are weaker fliers. They have long thin abdomens which are usually brightly colored and thin narrow wings. The wings are one of the easiest ways to distinguish between the two groups, especially when the insects are at rest. Damselflies have four wings, which are paired and are all the same shape. Most species rest with the wings held along the length of the abdomen, whereas dragonflies rest with their wings held open. Some species of damselfly do rest with their wings partially open, the Emerald Damselfly for example, a habit which gives rise to its North American name, Spreadwing. Both sub-orders have large compound eyes, ideal for hunting, but in dragonflies they are very close together, often touching. Damselfly eyes are always distinctly separate and never touch.
Damselflies and their larva, known as nymphs, are voracious hunters and will attempt to eat anything smaller than themselves. In common with dragonflies there is no pupal stage in the damselfly life cycle. Eggs are laid, the nymphs emerge and may molt several times, but do not form a pupa or cocoon. The adults emerge directly from the nymph. The eggs may be laid directly underwater or attached to underwater vegetation. The nymphs emerge after 2-5 weeks and may spend up to two years actively hunting underwater, breathing with the aid of external gills situated near the rear of the abdomen. Eggs laid late in the season will not hatch but will over-winter to hatch the following spring. When ready, the nymph will climb out of the water and undergo a final molt to reveal a young adult.
At this stage they are at their most vulnerable, as they must fill their wings with fluid to extend them and then wait for them to dry out before they can take to the air. The larval cases of damselflies can often be seen still attached to plants' stems after the adults have flown. When they first emerge damselflies are not yet sexually mature, and their colors are pale. Within a week the adults mature. Now sexually active, their colors are at their brightest. In relation to the nymph stage, adults on the wing live for a very short time, in some species a matter of weeks only. In this time the adults still actively hunt and feed. Damselflies will often wait in vegetation and ambush prey on the wing, whereas dragonflies are more active hunters, actively chasing their prey in the air.
Pairs of damselflies can often be seen on the wing, mating. Joined together at the ends of their abdomens, an arrangement known as the ‘wheel position’. Females will often lay their eggs whilst still attached to males in this way, either perched on submerged vegetation, or hovering over the surface of the water. The females of certain species may submerge for up to an hour to lay their eggs on the bottom of pools or streams.
Damselflies are found all over the world and are fascinating creatures, none more so than the largest damselfly, Megaloprepus caerulatus. Living in the rain-forests of Central and South America, adult males may have a wingspan of 7.5 inches, and they feed on orb-weaver spiders. Eggs are laid in temporary pools formed in holes in trees, and the nymphs will eat tadpoles and mosquito larvae. This is a fairly exotic example but there will be species of damselfly native to any locality, all well worth investigating further.