Giant Ichneumon Wykeham Forest

Rhyssa persuasoria also known as the Sabre Wasp or Giant Ichneumon is the UK's largest species of ichneumon wasp, in fact its probably amongst the largest insects in this country. This is a fairly local species, but one that is widespread and can be abundant where it occurs. I have had very mixed fortunes with this species over the years and have never got chance to take any decent photographs of it, until today where the very confiding individual below was observed.  

This species is primarily associated with coniferous woodland locally and to a lesser extent mixed areas of woodland. It seldom seems to occur in purely deciduous woodlands and subsequently this influences its distribution, with really good populations present in the vast areas of mixed forest bounding the edges of the North York Moors. The species is predominantly on the wing in July and August, at the peak of the summer months. 

As with other ichneumons this species is parasitic although not on the moths more typical of the family but predominantly on the giant horntail sawfly, as well to a lesser extent on longhorn beetle larvae. The wasp looks for areas of deadwood, predominantly fallen logs, containing host larvae and uses its long ovipositor to drill into the log and then into the larvae to lay an egg within it. The egg hatches and consumes its host whilst still alive in true alien science fiction style, typical of this family.  

Unlike many other ichneumons this species does not visit flowers but instead feeds on honeydew (secreted by aphids) on leaves. This is exactly what this individual was doing on a Sycamore. The insect was slowly and methodically walking over the leaves surface lapping up the honeydew. I suspect this behaviour often makes them quite hard to spot with a tendency to remain higher up in the trees canopy feeding, rather than coming down to flowers.