The beautiful and spectacular dragonflies and damselflies that add a splash of colour to our ponds and ditches in the summer spend most of their lives underwater as a dull brown or greenish nymphs (larva). Why do you think that the nymphs are such a dull colour? We have many damselfly nymphs during the RLL school visits but only one dragonfly nymph so far.
The nymphs of both dragonfly and damselfly are ferocious predators that actively stalk their prey which includes the newly hatched frog tadpoles, fish and other insects that live in the pond. They move slowly, climbing through the vegetation on their long legs, camouflaged by their dull colouring. While most damselflies usually complete their development from egg to adult in a year some dragonflies may spend 2 years or more as a larva before becoming an adult.
In late spring the nymphs of some damselflies starts to emerge. The larvae shed their skins many times to grow to full size, and as they near the time they will leave the water they develop ‘wing buds’ The earliest species to emerge is the is the large red damselfly.
Dragonfly nymphs are bigger and chunkier than the more slender damselfly larvae. They breathe by opening and closing the end of their abdomen taking water to the ‘rectal gills’ inside. The water can be sucked in and forced out quickly allowing the nymph to swim using jet propulsion over short distances. This is particularly useful for escaping danger.
Damselflies have three leaf-life gill plates that can be seen on the end of the abdomen. A gill plate can be shed if it is grabbed by a predator and sometimes we find damselfly larva with one or more gill plates missing. Like other insect larvae, the damselfly nymph sheds its skin to grow. This is called a moult. Any lost gill plates will grows back when they moult.
The damselfly can also use its gill plates as paddles as they swimming in an awkward s-shaped movement. The gills of damselflies and dragonflies are also known as tracheal gills as they are attached to their breathing tube system.