First of all I have to say that I like receiving such requests - I may not always have much time to devote to them, but I do try, and am always pleased that someone has put in the effort, and been interested enough, to photograph an invertebrate and then (often after having tried a general insect book and the web) bothered to find someone - me - to contact. Much better than squashing the unknown!
So, when my mother-in-law got in touch a few days ago saying that a guy (Scott, if you're reading this) doing hedge-trimming had found (and I paraphrase here) 'a big insect like a dragonfly with a stinger' on his leg, it was good to know that it had been put on a leaf and photographed. My initial thought was 'ichneumon' because dragonflies are pretty straightforward to recognise as a group (including the damselflies) and Britain doesn't have many other long, thin, large insects with anything resembling a 'stinger'. I wasn't sure how far I'd get with identification - with around 3,300 species in the UK alone, many of which are very similar, and no single guide to them, it isn't an easy task even with a specimen - from a photo, species-level ID is usually impossible. Still, I was curious and asked for the photos to be emailed to me, and this is one of the set I received...
|The mystery ichneumon|
|Side view of the mystery ichneumon|
Whichever it is, the specimen is certainly impressive. I find this group of insects intriguing and am slowly learning to identify them - it's a long process - and the species-level names are often indicative of their parasitic reproductive strategy and habit of hunting openly and actively for hosts; instigator, punctator, divinator, fornicator, consortana, dissoluta, inquisitor, insertana and so on. If you are interested, Broad (2006) provides a useful test key to subfamilies here. Beyond that, it's a matter of accumulating useful webpages, books and articles, and finding hymenopterists to help you - Fitton et al. (1988) shouldn't be too hard to find and covers the subfamily Pimplinae, members of which are quite readily encountered, such as the one below which took shelter in our bedroom while we were on holiday last month...
|A pimpline ichneumon, possibly genus Pimpla.|
Broad, G. (2006). Identification key to the subfamilies of Ichneumonidae (Hymenoptera). Available online here.
Fitton, M.G., Shaw, M.R. & Gauld, I.D. (1988). Pimpline Ichneumon-flies. Hymenoptera, Ichneumonidae (Pimplinae). Handbooks for the Identification of British Insects 7(1): 1-110.