Ovipositing Sabre Wasp from England

Subject: Please can you tell me what this is?
Location: Dalby forest. England
August 13, 2016 8:50 am
Saw this in the summer in north east England in a dense forest.
Signature: Perplexed

Sabre Wasp
Sabre Wasp

Dear Perplexed,
This is a parasitoid Ichneumon, the Sabre Wasp,
Rhyssa persuasoria, in the act of ovipositing, and you can verify our identification on Bio Images.  According to Bug Life:  “Wood drillers Ichneumons often locate their host species by ‘smelling’ them and this is exactly what Sabre Wasps do. Female Sabre Wasps locate the wood-boring larvae of the huge and beautiful Horntail Wasp (Uroceris gigas) by using their antennae to detect scents that emanate from the larvae’s wooden tunnels.  When a female Sabre Wasp has located a promising site, she starts tapping on the surface of the wood with her antennae. She then uses her long egg-laying tail to drill a ‘probe’ hole. She may drill a few probe holes before deciding on an appropriate position, and then drills as deep as she can. After 30-60 minutes, if successful, she will breach the tunnel wall, sting the larvae and then lay an egg on its body. With the larvae paralysed by the sting, it awaits the inevitable demise of being consumed alive by the Sabre Wasp grub.”  Your image is gorgeous, and though we have many similar looking images of North American relatives called Stump Stabbers in the act of ovipositing, your image is the first European example we have of your Sabre Wasp in the act of laying eggs.

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