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Life in Freshwater

Damselflies (Zygoptera)

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Common Blue Damselfly adult male
Adult blue damselfly (male) at rest

Coenagrions are the typical blue damselflies that one sees fluttering around the edges of water. They are sexual dimorphic i.e. the sexes differ in their appearance. The males are generally blue with a variety of black bands of which the pattern on the segment 2 is a good distinguishing characteristic. The patterns of black on the female is quite different, usually darker, with a background colour of green. Bodies are around 34mm long. The larvae when mature are up to 30 mm long

Larva (nymph) of a typical pond-dwelling damselfly
Larva (nymph) of a typical pond-dwelling damselfly

IDENTIFCATION:

Pair of damselflies mating
Pair of damselflies mating

Large Red Damselflies (Pyrhosoma nymphula) egg laying on Potamogeton pond weed
Pair of Large Red Damselflies (Pyrhosoma nymphula) egg laying on Potamogeton pond weed

ECOLOGY: Most damselflies have a strong fluttering flight. and the larvae live amongst the aquatic vegetation of Elodea and Milfoil feeding on a range of insect prey, including mayfly and midge larvae. The develop within a year and emerge from the pond, climbing on to plants above the water surface. They leave the pond, especially the females, travelling up to a kilometre into meadows and scrub to mature. The males quickly establish a territory and the females, after about a week, join them. The male catches them as they pass through the territory. As in all Odonata the male has 2 sets of genitalia. The first is at the end of the abdomen where sperm is first appears. The second set are located underneath the 2nd and 3rd abdominal segments. The claspers at the end of the abdomen grab the female at the back of the neck and in this form (tandem) they fly and lay eggs (see picture). Mating is achieved when the female places her abdomen underneath his 2nd pair where the penis is located. Sperm would already have been transferred from the first set to this prior to mating. Mating takes up to 15 minutes. The eggs are laid by the female inserting them into the submerged vegetation.

Banded Damoiselle (Agrion splendens)
 Banded Damoiselle (Agrion splendens): male on territorial perch by a river

Larve of Agrion
Larve of Agrion, found in fast flowing water

See also Dragonflies (Anisoptera) which are a similar group.

 Classification:

 

 Kingdom

Animal

 Phylum

Arthropoda

 Class

Insecta

 Order

Odonata

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