Giant ichneumon fly/wasp, sabre wasp
This parasitic species is the largest ichneumon fly in Britain, and one of the largest in Europe.
Meaning of scientific name
The scientific name means 'persuasive burglar'.
Length approximately 18-40mm, plus 40mm ovipositor.
Giant ichneumons have slender bodies, with a wasp waist, and long, flexible antennae. The apparently fearsome-looking sting at the end of the female wasp's abdomen is actually an ovipositor (egg-laying instrument). This is protected within a sheath. This species has a black body with pale yellow/white markings on the abdominal segments. The legs are orange.
Giant ichneumon flies are found in Europe, north Africa, North America and Asia.
They inhabit clearings, tracks and footpaths in coniferous forest.
The ichneumon larva feeds on the body tissues of the host until fully grown.
Ichneumons are parasites that lay their eggs in or on the larvae of other insects or spiders. The hosts of giant ichneumons are usually the larvae of horntails, or wood wasps (Orocerus gigas), and related species, as well as the larvae of longhorn beetles (Monochamus sutor). The female looks for hosts, which live within fallen timber. She may detect them through the smell of their droppings, which are then contaminated by fungi, or by sensing their vibrations within the wood. However she does it, the accuracy with which she locates them is remarkable. When she finds the right spot, she drives her slender ovipositor into the wood (which can be inches thick) by rotating the two halves backwards and forwards very rapidly. She lays one egg next to or on the host larvae. The whole process takes about 20-40 minutes. When the fly larvae hatches it feeds externally on the host. It overwinters and pupates in the spring before emerging from the wood. Giant ichneumons sometimes emerge in houses from furniture made from new timber. The adults are active from July-August.
Giant ichneumon flies are common in the UK and are not listed in the IUCN Red List.
There are about 60,000 species in the Ichneumonidae family. They are part of the Hymenoptera order, which includes wasps, ants and bees. Giant ichneumons are harmless to humans.