Backswimmer ID

[serendipity]

Is this Notonecta glauca or N.viridis? i know it is most likely the former but only distinction i can find between the two is shape of pronotum and the spike going down behind eye for viridis which this appears to have! not many pictures of viridis on web either, though i did come across a handy key to water bugs!

[RobSutton]

I've copied this out from Southwood & Leston's - Land & Water Bugs of The British Isles. They have 4 Notonecta species?

1. Anterior angles of pronotum finely pointed and produced forwards, partly embracing the sides of the eyes; bugs usually less than 14.5 min. long (Forewings with a small dark streak adjacent to the membrane) - marmorea

Anterior angles of pronotum not sharply pointed and produced; bugs usually more than 14.5mm.long GO TO 2

2. Metanotum (seen when the wings are moved outwards) orange with a pair of black spots; forewings largely mottled -maculata

Metanotum black; forewings seldom mottled save for small patches GO TO 3

3. Forewings black with the clavus and an oblique streak near the inner angle of the corium pale - obliqua

Markings of forewings of other forms but usually pale with a few dark markings - glauca

It's hard to say without the specimen in hand but following the key could lead you to marmorea if I'm reading the pointed projections of the pronotum and dark fleck on the wing correctly. I'd await confirmation from one of our "bug" experts though. Now whether this is now called viridis is another question? A problem when relying on old books!

Reading a bit more I think N.viridis was called Notonecta marmorea ssp. viridis once upon a time.

[Dogghound]

Keys out at and looks very good for Notonecta viridis, I have to ID alot of these for HLS pond management plans, although always with actual specimens, IDing from photo's is always harder.

[serendipity]

Thankyou both!