Red-eyed Damselfly
Erythromma najas
The Red-eyed Damselfly is a species of damselfly in the family Coenagrionidae. Males are easily identified by their striking deep red eyes and blue markings at the tip of an otherwise dark abdomen. They primarily inhabit still waters with extensive floating vegetation, such as water lily pads, which they use as perches.
Details
Identification
Males: bright red eyes, abdomen top black, segments 1, 9, and 10 blue. Females: eyes brown above, yellow-green below, body bronze-black with pale sides.
Social behavior
Males are territorial and defend individual floating leaves against conspecifics.
Diet
Larvae feed on aquatic invertebrates such as small crustaceans; adults hunt small flying insects like midges.
Hunting strategy
Ambush predators (larvae) and perch-and-wait hunters (adults) that catch prey in flight.
Spawning substrate
Eggs are laid endophytically into the tissue of floating-leaved plants (e.g., water lilies).
Overwintering
The species overwinters as a larva in the water, usually in the sediment or on aquatic plants.
Ecology
Ecological role
Important predator in aquatic and terrestrial food webs, also serving as prey for birds and fish.
Natural predators
Birds, frogs, larger dragonfly species, and fish (for larvae).
Competitor species
Small Red-eyed Damselfly (Erythromma viridulum), other damselflies.
Ecosystem service
Regulation of insect populations (e.g., mosquitoes).
Threats
Loss of still waters with floating vegetation, eutrophication, and removal of aquatic plants.
Scientific profile
Profile
Distinguishing features
Larger than Erythromma viridulum. Males lack blue wedge-shaped markings on the sides of the thorax; no pale postocular spots on the back of the head. The blue coloration at the tip of the abdomen covers only S9 and S10, while S8 remains black.
Role in food web
Secondary consumer; predator of zooplankton and smaller insect larvae; itself prey for fish and larger dragonfly larvae (e.g., Aeshnidae).
Protection & threats
Main threats
Loss of floating-leaf zones due to eutrophication, intensive fishery management (grass carp stocking), and mechanical disturbances (boat traffic).
Population trend
Stable; tending to increase in some regions due to climate warming and northward expansion.
Conservation measures
Preservation and promotion of floating-leaf communities; reduction of nutrient inputs; restriction of boat traffic in littoral zones.