hbrook1's picture

Female Common Blue Damselfly (Enallagma cyathigerum)

Observed: 15th July 2013 By: hbrook1hbrook1’s reputation in Invertebrateshbrook1’s reputation in Invertebrateshbrook1’s reputation in Invertebrates
robbie damselfly
Description:
Identifications
Species interactions

No interactions present.

Comments

chrisbrooks's picture

ID comment

The wide antehumeral stripes, the triangular mark in abdominal segment 8 and the "V2" rocket shapes in S3-S7 help identify the female of this species.

hbrook1's picture

Sorry, didn't see this before

Sorry, didn't see this before posting my query. Thanks very much!

hbrook1's picture

How do you tell the

How do you tell the difference between a white-legged damselfly and a common blue female?

chrisbrooks's picture

ID links below

hbrook1's picture

My friend whose photo this is

My friend whose photo this is is not convinced this is a female common blue- these are his reasons:

"I will stick by my classification as a Whitelegged Damselfly (Platycnemis pennipes).
The question is why I think this.
I have zoomed in on the photos to try to capture diagnostic info but the angle isn’t quite right for 100% accuracy. The Bluets are, I think, Variables (Coenagrion pulchellum).
The photos of the Whitelegged Damselflies [and Bluets] were taken on a warm sunny day [in Writtle, Essex].
The colour difference between the species is quite startling (which is why I took the photo) but the size is very similar. Both species were present in the area. When seen next to a Bluet the Whiteleg looks finer or more delicate. The tail segments seem thinner than on the Bluets.
The head colouring is clearly white and there appears to be a black band across it but it is not possible to tell if it is in front of or between the ocelli. Anti-humeral stripes are present, three are visible with a pale stripe between the upper two, this suggests two pairs on the thorax. Pterostigma are present but are not usable for diagnostic purposes (as they are in the same position on other species), likewise the black markings on the segments are visible but the angle is not good and the really diagnostic colouration is on the top of the segment. The legs look as if they are covered in white bands, these would be the bristles that give it its alternate name of featherleg.
I think that there are enough similarities between these photos and the descriptions in Dijkstras’ Field Guide to the Dragonflies of Britain and Europe (2006) to be able to say that it is a Whitelegged damselfly rather than a Bluet."

I don't know enough about common blues or white-legged damselflies, so I thought I would ask your opinion. Do you think he's right? If not, why not? Many thanks!

RoyW's picture

ID.

I realise that this is an old post (I've not been on Ispot much recently), but Chris is correct and your friend is not.

This is a female Common Blue damselfly for the reasons Chris stated. A White-legged Damselfly/Blue Featherleg would not have anywhere near as much black on the upper side of the abdomen segments, would have a very different thorax pattern, and would have pale or brown pterostigma.

chrisbrooks's picture

White legged Damselflies

Hi, the White-legged Damselfly is unique in that it has a double antehumeral stripe. This specimen has one wide stripe, I refer you to the ID links I posted above. This is a female Common Blue Damselfly for the reasons I initially gave. I hope that helps, regards Chris.