Scarce Emerald Damselfly
Lestes dryas
The Scarce Emerald Damselfly is a medium-sized damselfly characterized by its metallic green body and blue pruinosity on the abdomen of mature males. It typically inhabits small, still water bodies that may seasonally dry out, showing a preference for dense emergent vegetation. Distributed across the Holarctic, it is often used as an indicator species for healthy, seasonally fluctuating wetland ecosystems.
Details
Identification
Metallic green coloration, wings held half-open at rest, male inferior anal appendages are spatulate (spoon-shaped) at the tips.
Social behavior
Solitary; males defend small territories in shore vegetation; mating occurs in tandem formation.
Diet
Predatory; larvae feed on aquatic insects, small crustaceans, and tadpoles; adults catch various flying insects.
Hunting strategy
Perch-and-wait predator; the damselflies wait on stems for prey and capture it in short pursuit flights.
Spawning substrate
Eggs are inserted into the tissue of emergent plants like rushes, sedges, or reeds above the water level.
Overwintering
Overwintering occurs exclusively in the egg stage, which enables survival in water bodies that dry out in summer.
Ecology
Ecological role
Important predator in small aquatic and terrestrial systems; serves as a food source for birds and amphibians.
Natural predators
Birds, frogs, larger predatory dragonfly species, spiders.
Competitor species
Emerald Damselfly (Lestes sponsa), Southern Emerald Damselfly (Lestes barbarus).
Ecosystem service
Natural pest control by consuming mosquito larvae and other insects.
Threats
Destruction of wetlands, lowering of groundwater levels, intensive agriculture, and eutrophication of water bodies.
Scientific profile
Profile
Distinguishing features
More robustly built compared to Lestes sponsa. Males: The superior anal appendages are spatulate (spoon-shaped) at the tips and curved inward, touching each other. Females: The ovipositor is remarkably large, extending beyond the tip of the tenth abdominal segment.
Role in food web
Secondary consumer; regulates insect populations in small water bodies and serves as prey for higher predators.
Protection & threats
Main threats
Drainage of wetlands, lowering of groundwater levels, loss of small water bodies through succession or infilling, intensification of agriculture (eutrophication).
Population trend
Regionally declining in Germany and often on the pre-warning list or classified as threatened, globally stable.
Conservation measures
Protection and creation of temporary small water bodies, preservation of sedge marshes, avoidance of drainage measures near bogs, creation of buffer zones.