Ichneumon or maybe Sawfly

[Gateside]

I first thought this must be a sort of Ichneumon, since it has a thick leading edge to the forewing, and prominent stigma.
However, it does not have a narrow waist, and I see some sawflies have the features I've noted above anyway.

The obvious features are:
a) almost all orange
b) yellow spot at lower end of thorax
c) small dark area at tail tip
d) large yellow and black stigma

Images not clear enough to make any conclusions about venation, I suspect.

I guess it can't be identified, but it would be nice to know what class to put it in.

Nigel

[Jason Green]

I was all but ready to say 'Cynipid' from the thumbnails. Looking at the full images it lacks a restricted waist, so is a Sawfly.

[poschiavanus]

Any idea of the size?

I can make out 9 antennal segments, but can't decide if there is a vein running from the outer end of the stigma (). Given that around 80% of the British List are Tenthredinidae its most likely to be this anyway, but eliminating Nematinae would reduce the options to something more manageable.

I do know one sawfly genus which has species with two-coloured stigame : Tenthredopsis. A couple of provisionally IDed species from Leicestershire: T. nassata, T. litterata, and a few from Belgium. Of course there may well be other species with this character.

[Jason Green]

Nematinae was one idea I had. Yes, it would be reduced to a smaller group - but all I've heard of these are how specialist they are even with specimens.

I think your observation of the bi-coloured stigma is most pertinent, though.

[Gateside]

I've re-visted my photos, and had a look at the possibility of a vein from the stigma to the wing's end. There is one visible in another photo that is otherwise more blurred. It runs diagonally from about where the yellow changes to black on the outer side of the stigma, and meets a radial vein.

The size of the insect can be judged by the fact that those are hefty grass stems - the round one it's on is probably about 4 mm diameter.

Does any of this help? Myself, I think the bi-coloured stigma is the best clue.

Nigel

[Gateside]

Having just looked at the two suggested sawflies, I think the fact that T. nassata has a black and yellow head eliminates that one. T. litterata has a variation of colouring, and so might be it. Might! Right habitat too.

This is further than I thought I might get.

Nigel

[poschiavanus]

Originally Posted by Gateside

Having just looked at the two suggested sawflies, I think the fact that T. nassata has a black and yellow head eliminates that one. T. litterata has a variation of colouring, and so might be it. Might! Right habitat too.

This is further than I thought I might get.

Nigel

I wish it was that simple. There's far too little information about colouration of these species available to me, and Benson's key hardly mentions any macroscopic features at all. Unlike many sawflies there are very few images on the internet so I'd think Tenthredopisis is not straightforward: for all I know there might be several other genera with the bi-coloured stigma.

Hopefully, this characteristic will now stick in a few people's minds and enable them to check other features when they come across similar insects in the future. With other groups this has resulted in a good improvement in available information in quite a short time-span.

[Gateside]

Don't worry - I'm not taking any firm line on what has been suggested as an ID. But the image of T. litterata that had a link to the web had an area below the obvious pale spot on the thorax where there appeared to be 4 faint oblong-ish blobs forming a circular area. In fact my image has the same feature, which I only noticed by altering the brighness using Photshop. Another interesting similarity. But I agree that other species, even in another group, might have something similar.

It is a bit exasperating: that all I have from this sawfly, and several Ichneumonids, is nothing. The Ichneumonids are all clearly different, and one has great detail, but that is as far as it goes. I can't record anything.

Nigel

[Jason Green]

Originally Posted by Gateside

It is a bit exasperating: that all I have from this sawfly, and several Ichneumonids, is nothing. The Ichneumonids are all clearly different, and one has great detail, but that is as far as it goes. I can't record anything.

If you felt suitably serious, you could always - collect specimens, locate the ID literature, key them out to species-level using a microscope and gain real insight. All the British experts have done this if their group needs it

I used to be a field-photographer and found it to be a great entry-point. The photos were good, it provided a nice talking-point when people came across me out-and-about and was something you learnt a skill from. There's a great many you can do photographically. However, when you become increasingly serious you realise that for proper study it just isn't feasible. I now wince when I remember thinking 'Andrena is impossible'. Now, it isn't - I was just using the wrong tool, a camera.

Either way, you have the right approach - accepting the limitation your otherwise enjoyable hobby possesses, and not 'pushing the boundaries'

[Gateside]

I do agree with what you say about getting into things properly through examination of specimens, at least with a decent hand-lens.

On the other hand, I have found so many orders of insects (and some non-insect species) interesting, and capable of resolution by good photos, that I would not be able to concentrate on any one order. There would simply not be enough time. I am already at capacity (my wife would claim she is already a wildlife widow!). So I think I am more useful identifying a considerable range of wildlife adequately, than becoming focused on one of two orders at most, and maybe becoming an expert, or maybe not.

So I'm going to stick with being a generalist!

Nigel