Emerald Damselfly

Lestes sponsa

Also known as the spreadwing as it belongs to a group of damsels which mostly perch with their wings open like a true dragonfly, rather than held closed along the length of the abdomen like most other damsels.
Their metallic green casings make them unlikely to be confused with any other species (in our region at least), the only other metallic green damsel being the female Banded Demoiselle, but colour is the only thing they have in common, the demoiselles are obviously bigger, longer legged, are green in their entirety and the wings are very large in comparison and tinted green, plus they are usually only found on rivers, emeralds very rarely are.
The last of the damsels to emerge, they aren't usually seen until July, and will be the only damsel remaining in late season, lasting through September.

In Gateshead they are usually found in small numbers at most sites, but my favourite site for them is Gibside's Lily Pond, where they seem to thrive and are easily photographed perched and in tandem in vegetation close to the water's edge.

Emerald Damselfly (mature male)
A typical male in his prime, bright green metallic body, slender abdomen
ending in a blue tip. Blue on thorax and first two segments of
abdomen also.
The species is not a strong flyer so perches a lot around pond margins,
often in dense vegetation, with wings half to fully open.
This closer shot shows his superb colouration, deep blue eyes,
iridescent green thorax with sky blue pruinescence.

Immature male
Note lack of blue, as this is a pruinescence forming during the
maturation period, which is about 16 days.

Over-mature male
Emeralds are long-lived individuals so late in the season look out
for dull bronze specimens of both sexes, which could be up to
10 weeks old. 
Mature male perched with wings
typically half open. They usually roost next to the water
like this but in thicker vegetation. 

Emerald Damselfly (mature female)
Darker or duller green than the male with pale cream/pink
replacing the blue pruinescence.
And just to prove they don't always perch with wings spread,
here is a female doing just that.

immature female
Colouration is much the same as immature
male but the abdomen is noticeably thicker and is tip-heavy. 

Tandem pairs are formed anywhere where the vegetation
is dense enough, and copulation takes at least half
an hour, often a lot longer.
Pairs stay in tandem for ovipositing, edging down
the plant stem and into the water, sometimes both
parties becoming totally submerged.
This over-mature female (told by the deep bronze
colouration) is ovipositing alone, more common in older
The Emerald has a one-year life-cycle. Eggs over-winter, hatching in April and larva develop according to temperature, taking over 2 weeks longer in the north than south to reach the final instar and emerge by late June-mid July.﻿﻿

No comments:

Post a Comment