Given the diversity of dragonfly and damselfly species, it's no surprise that they also lay their eggs in a variety of ways, with differences in interactions between males and females during oviposition and variations in egg-laying sites and behaviors, egg placement, number per clutch, and time to hatching.

Egg-laying begins soon after copulation ends. Eggs can be inserted into living or dead plants or punky moist wood (endophytic oviposition), laid in or on water or mud, above the water where the newly hatched prolarvae can drop onto the water's surface, or in soil in temporary wetlands where they will hatch upon being rewetted (exophytic oviposition). A female may mate more than once and lay multiple clutches of eggs. Depending on species, a female dragonfly or damselfly can lay hundreds to thousands of eggs, at rates ranging from 1-18/minute in endophytic species to over 1000/minute in some exophytic species. This sheer number of eggs is sometimes revealed in a startling way, as a gravid female dragonfly caught for in-hand examination may suddenly begin extruding eggs. Females (and their mates) are at higher risk of predation as they engage in egg-laying, and a batch of eggs may be gulped up by a passing fish, so many odonate species scatter or place their eggs in several different places within suitable habitat to better hedge their reproductive bets.

Oviposition is the province of females, but is also associated with a variety of male behaviors. In some species, the female lays eggs alone, although her oviposition may be interrupted periodically to flee approaching males. Conversely, males of some species engage in contact-guarding, remaining in tandem with the female as the pair flies off to lay eggs. In others, the male releases the female after mating but does hover-guarding, remaining in the vicinity and darting out to shoo away males who try to interfere or mate with the female. Some species oviposit in aggregations, which are thought to reduce the risk of being eaten by predators, and rows of damselflies in tandem all busily ovipositing is a delightful sight while out canoeing or kayaking.

All damselflies are endophytic, as are some types of darners (including our migratory Common Green Darner). Females of endophytic species generally have a thorn- or needle-like ovipositor to cut small slits into plant material where eggs are laid. Damselflies often begin their egg-laying on emergent vegetation and then back down the stem, laying eggs as they go, until they are submerged; they can stay underwater for several minutes up to an hour, likely obtaining oxygen from a bubble of air trapped around their bodies and wings. A contact-guarding male that is being pulled along may release the female but remain in the vicinity until she emerges again.

Exophytic females extrude eggs from a genital pore on the underside of abdominal segment 8; they may then tap their abdomen against the water to dislodge eggs or drop balls of eggs over the water (or over dry land, in the case of some meadowhawks) at intervals. Exophytic species lack the cutting ovipositor of endophytes, but some, including species of meadowhawk (Sympetrum), emerald (Somatochlora), and spiketail (Cordulegastridae), have an enlarged subgenital plate on the underside of the tip of the abdomen that helps push or tap eggs into soft substrates. A female Autumn Meadowhawk (Sympetrum vicinum) is easily recognizable by her large, scoop-shaped subgenital plate, into which she extrudes balls of eggs to be tapped onto the water or shoreline. Females of some species will first scoop up a drop of water, then extrude some eggs into the droplet and flick the whole ball towards the shoreline or onto the water.