Damselfly (Zygoptera) 


Damselflies are hemimetabolous (“half change”) organisms, meaning they undergo incomplete metamorphosis during their life cycle.  During incomplete metamorphosis, the organism does not go through larva and pupa stages; instead, it goes through multiple molts during a nymph stage.

Depending on the species, adult damselflies are most active during spring, summer, or fall.  Damselfly pairs often fly while mating and may remain clasped in tandem for hours.  The male damselfly grasps the female behind her head with claspers on his abdomen; he then deposits sperm by bending his abdomen forward since the male sex organ is in the front part of the abdomen.  The female loops her abdomen to receive the sperm from the male.  It is common for damselflies to produce one generation each year, but it may take 1-2 years to complete the life cycle. 

Once fertilized, females usually lay eggs by dipping their abdomen into water; the chosen habitat for the eggs can vary widely from underwater vegetation, above water vegetation, water-filled cavities, or bromeliads. 

A naiad (nymph) emerges from the egg to enter the aquatic nymphal stage which can last anywhere from a few weeks to almost five years, never leaving the water.  The naiad goes through 10 – 15 instars, or molts, to grow before being mature enough for the next stage; after each instar, the naiad becomes darker.  During each molt, the exoskeleton hardens, and the wings develop as buds on the thorax until they are functional.  Developmental rates are intimately related to seasonal cues which send signals to hormones in the naiad.  When naiads hatch late from their eggs, their development time decreases; this results in a larger adult body size because the growth rate increased by such a large amount.  At the other end of the spectrum, larva that hatch early can afford to slow their development rate because they lack the motivating pressure to maximize growth rate.  Naiads slow their growth to also decrease mortality risk.

After the naiad completes its instars, it swims to the water’s edge and crawls out of the water onto a plant.  This often occurs as the sun warms the habitat after sunrise; this timing helps the damselfly avoid dew because dew can be fatal if it touches the damselfly’s wings while it emerges from its naiad form.  After the naiad’s skin dries, the skin splits along the wing case as the adult strains to pull away from the old skin.  The adult damselfly’s new legs harden while attached to the plant, and the wings slowly expand as fluids from the abdomen pump them open.

Finally, the wings dry, and the adult damselfly can fly into its terrestrial environment to complete the rest of its life.  The damselfly can exist in its adult form for several weeks or months before mating and dying.

Want to follow damselflies as they complete their life cycle? Sure you do! Just follow this link.

Damselflies cannot be the only organisms that live near water! Find out more about the other aquatic organisms that live with (and sometimes eat) damselflies.