The Dragonfly Life Cycle

Egg Stage

Mated dragonflies and damselflies deposit their eggs in, on, or near the water, depending on the kind of odonate.

Most odonate species are endophytic ovipositors, meaning they insert their eggs into plant tissues using well-developed ovipositors. The female typically slits open the stem of an aquatic plant just below the waterline and places her eggs inside the stem. In some species, the female will briefly submerge herself in order to oviposit in a plant well below the water's surface. Endophytic ovipositors include all damselflies, as well as petal tail dragonflies and darners.

Some dragonflies are exophytic ovipositors. These dragonflies deposit their eggs on the water's surface, or in some cases, on the ground near the pond or stream. In exophytic ovipositors, the females extrude eggs from a special pore on the underside of the abdomen. Some species fly low over the water, dropping eggs at intervals into the water. Others dip their abdomens into the water to release their eggs. The eggs sink to the bottom or fall onto aquatic vegetation. Dragonflies that oviposit directly into the water may produce thousands of eggs. Exophytic ovipositors include clubtails, skimmers, emeralds, and spiketails.

Unfortunately, dragonflies cannot always distinguish the surface of a pond from other reflective surfaces, like the shiny finishes on cars. Dragonfly conservationists are concerned that manmade objects may be putting some odonates at risk of decline because female dragonflies have been known to deposit their eggs on solar panels or car hoods instead of in ponds or streams.

Egg hatching varies considerably. In some species, eggs may hatch in just a few days, while in others, the eggs may overwinter and hatch the following spring. In dragonflies and damselflies, a prolarva hatches from the egg and quickly molts into the true larval form. If the prolarva hatches from an egg that was deposited on the soil, it will make its way to the water before molting.

Larval Stage

Dragonfly larvae are also called nymphs or naiads. This immature stage looks quite different from the adult dragonfly. All dragonfly and damselfly nymphs are aquatic and remain in the water until they are ready to molt into adulthood.

During this aquatic stage, odonate nymphs breathe through gills. Damselfly gills are located at the end of the abdomen, while the gills of dragonfly larvae are found inside their rectums. Dragonflies pull water into their rectums to respire. When they expel the water, they are propelled forward. Damselfly nymphs swim by undulating their bodies.

Like adult dragonflies, the nymphs are predators. Their hunting methods vary. Some species lie in wait for prey and hide by either burrowing in the mud or resting within the vegetation. Other species hunt actively, sneaking up on prey or even swimming in pursuit of their meals. Odonate nymphs have modified lower lips, which they can thrust forward in a split second to grab a passing tadpole, arthropod, or small fish.

Dragonfly nymphs molt between 9 and 17 times as they grow and develop, but how quickly they reach each instar depends greatly on the climate. In warmer climates, the larval stage may take only a month, with the nymph growing rapidly. In the coldest regions of their range, dragonflies may remain in the larval stage for several years.

During the final few instars, the dragonfly nymph begins to develop its adult wings, although they remain tucked inside wing pads. The closer to adulthood the nymph is, the fuller the wing pads appear. When it is finally ready for its last molt, the larva crawls out of the water and grabs hold of a plant stem or other surface. Some nymphs travel quite far from the water.

Adult Stage

Once out of the water and secured to a rock or plant, the nymph expands its thorax, causing the exoskeleton to split open. Slowly, the adult emerges from the cast skin (called the exuvia) and begins to expand its wings, a process that may take an hour to complete. The new adult will be weak and pale initially and only have limited flying ability. This is called a teneral adult. Teneral adults are more vulnerable to predators, as they have softer bodies and weaker muscles.

Within a few days, the dragonfly or damselfly usually exhibits its full adult colors and gains the strong flying ability that is characteristic of odonates. Having reached sexual maturity, this new generation will start searching for mates and begin the life cycle again.

Sources

• _{Borror and DeLong's Introduction to the Study of Insects, 7}^th _{edition, by Charles A. Triplehorn and Norman F. Johnson.}
• _{Dragonflies and Damselflies of the East, by Dennis Paulson.}