I saw this ichneumon in a bramble hedge on the Dorset coast last month. It was a good 30mm head to tail. In 75 years of watching insects I have not seen one like it in Britain. Can anyone identify it? And if so, what is its life history?
Well, it's like this...
Two people who know a great deal about ichneumons, especially in the UK, are
- Dr Gavin Broad (based at the NHM)
- Martin Harvey
Martin has written an essential read for anyone interested in British Ichneumons (Ichneumonidae)
It really is essential - Martin mentioned some key facts, which should be taken on-board before attempting to ID any ichneumon, eg.:
- there are ~3,000 species in the UK
- IDs often require microscopic examination
- field guides such as the Collins only get you a little way
- Gavin Broad's checklist of the British species of Ichneumonidae has 162 pages (no pictures)
- 'Chinery's photographic guide has a page of ichneumonids entirely incorrectly named'
- many ichneumons that look very similar are actually in different subfamilies (not even the same genera)
Read Martin's page to get the full picture, and for the useful links it contains.
(Thank you very much Martin and Gavin.)
Having said that, here are two web pages that include ichneumons that look very similar to yours
(you will have to scroll to find them).
But in both cases, they are un-named (sigh!)
You have taken an excellent photo. I just wish I could do it justice by IDing the subject for you!
It is really difficult - not knowing exactly what characters to pay attention to and how variable they may be, not knowing how far one can trust IDs of photos online, etc.
However, you could be right Florin; Therion circumflexum certainly looks a good match going on those photos and a few others I've found. To be sure, we'd have to compare with the type specimen and diagnosis (easier said than done, of course). Personally, I'd be happy just to go as far as Anomaloninae (Therion is one of several genera therein) (here's the US perspective on Anomaloninae - http://bugguide.net/node/view/319535/tree).
You could use Florin's ID as-is, or you could use it in the form 'aff. Therion circumflexum'.
[For aff., cf., ? and other terms of 'open nomenclature' see Peter Bengston's paper here - http://www.webcitation.org/5vxR3btgz.]
You could also refer to it as an anomaloninid wasp.
I note this paper, which you may have access to, Florin:
Gauld, I.D. (1976): The classification of the Anomaloninae (Hymenoptera: Ichneumonidae). Bulletin of the British Museum of Natural History (Entomology) 33: 1-135.
Thank you very much Mike for your comments on the identification of this magnificent ichneumon. I am grateful also to Florin for his remarks. The insect in the photo he refers to seems to be pretty well identical to the one I photographed. I propose to caption it: Ichneumon wasp (Anomaloninae - prob.Therion circumflexum).