Life Cycle of a Dragonfly
A Long Journey for an Ancient Insect
Dragonflies have been around for about 300 million years: long before the dinosaurs appeared. In the Carboniferous Period, they grew to have a wingspan exceeding two feet – probably because there was almost fifty percent more oxygen in the atmosphere than there is today, and possibly because there were no other flying predators to compete with and eat them.
These ancient dragonflies were so successful in their niche that dragonflies have not changed significantly and modern dragonflies have the same body plan with the same functions that the primitive dragonflies did. Both the larval and adult stages of dragonflies living today resemble those of the earliest dragonflies in the fossil record. “Modern” odonates are divided into three suborders: Zygomorpha (damselflies), Anisotropha (dragonflies), and Anisotrophomorpha (primitive dragonflies),
From the Egg
A dragonfly or damselfly begins life when a tiny egg arrives in the waters of a lake, pond, stream, or vernal pool. The voracious larva hatches out, respires using gills, feeds, grows, and eventually climbs out of the water, splits and crawls out of its skin equipped with wings and an air-breathing respiratory system. A successful adult feeds, matures, mates, reproduces, and dies – usually from depletion of resources after mating, but sometimes because freezing weather kills it.
Larval Body Plan
Odonate larvae are usually brown in color. Their bodies are flattened – sometimes grotesquely, and the six legs lie just behind the head. The naiads (damselflies) and nymphs (dragonflies) are quite different. A naiad is slender with three gill plates attached to the tip of the abdomen. A nymph is usually stout, sometimes almost round, and has two gill plates attached to its abdomen. Larvae of the several groups of odonates are distinctive, but each species also has a characteristic shape and/or projections that identify it.
All odonate larvae have chewing mouth parts and a hinged lower jaw that lies under its body. This jaw is attached just behind its mouth, extends backward between its legs, and doubles forward so that the pinching jaws lie below its mouth. The entire apparatus swings forward more than half the length of the body, and captures prey when fully extended.
Larval Growth
Odonate larvae grow at characteristic rates ranging from two months to several years depending on prey availability, water temperatures, and the ultimate size of the adult. As the larvae live in submerged vegetation or under debris at the bottom of the water, they feed continuously – even if there is an ice cover on the lake or pond.
Damselflies usually have a rapid life cycle. Spring adults often lay eggs producing larvae that develop into late summer adults in two or three months. Late summer adults lay eggs from which the larvae develop slowly as temperatures drop, and the next generation of adults hatches in the spring. Some damselflies and many dragonflies are only seen in the spring or in the fall. These species take about ten months to develop – although some will spend several years growing large enough to metamorphose. The largest dragonfly and damselfly species often require a minimum of three or four years of growth in warm climates, extending that to five to seven years in high latitudes.
Metamorphosis
Once the larva has reached its optimum size, it metamorphoses to an adult. This usually takes place in the morning on a day with bright sunshine.The larva crawls up the stem of emergent vegetation, its skin splits, and a pale insect with small wings emerges. Over a period of about an hour, the adult pumps body fluids and air into the wings as they inflate and then harden into the gossamer propellers of flight. During this period, the dragonflies are the most vulnerable to predation by birds and other insects including wasps and other dragonflies. Once the wings have expanded and hardened, the insect takes flight. Over the course of several days to a week, the body and wing coloration changes to indicate to others the dragonfly has matured and is ready to mate.
The adults, courtship, mating, and egg laying are described on page 2.
12-spotted Skimmer Female Laying Eggs
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Dragonfly Nymph
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