HYMENOPTERA > APOCRITA | Parasitica > Ichneumonidae > Tryphoninae > Phytodietini

Once again, which has been the case with a quite a few of the named species that I've been able to include in this section, this individual was identified by an expert on the 'British Ichneumonoidea' FB group as - Netelia for sure, very likely Netelia fuscicornis.

The latest checklist recognises at least twenty-two Netelia species with a few more that have been identified but, as yet, are unnamed. I believe that they all have similar pale dull-reddish colouration, which makes them almost impossible to distinguish without close examination. However, Netelia fuscicornis is possibly an exception as, apparently, it can be identified by a combination of visual characters, which in addition to the males having dark antennae, include the shape of the head, presence of strong scutellar carinae and specific details regarding forewing venation. Subsequent research led me to a 'key', which provided additional detail, such as the antennae having 44-51 flagellomeres with the first being roughly 4-5 times as long as broad but, understandably, not much else that could be used unless you were physically keying out a specimen rather than trying to make an assessment from a solitary photo.

The all-important wing venation was interesting though and worth noting for future reference, even though it took me a little while to work out what it actually meant; veins 2rs-m and 3rs-m delimiting narrow, triangular areolet = Netelia, and ratio of vein cu-a distal of Rs+M about 0.4-0.6 the length of cu-a = Netelia fuscocornis. I enlarged the shot and measured the vein lengths on screen and was pleased to find that they seem to correspond.

Another note regarding identification is that Netelia fusocornis has two generations a year, where individuals flying later, from the end of summer into autumn, will typically have a narrower head than those seen at the beginning of the season such as the one featured here that was photographed in early May.

Netelia fuscicornis is a koinobiont ectoparasitoid of Leptidoptera larvae, specifically of noctuid moths of the Mythimna genus, which breed and develop in soil. The female wasp will attack and temporarily paralyse a caterpillar with a sting so that she can lay her egg, which necessities puncturing the cuticle. The egg is stalked and remains firmly attached as the caterpillar continues to feed. It will only hatch once the host has formed a pupation retreat. The wasp larvae can then freely feed on the body as an external parasite until it is fully developed. The association between these species leads to Netelia fuscicornis being more frequently found in open habitat such as Hartland Moor where a number of these particular moths are known to occur.

Although this species is regarded as fairly common and widespread, it's only been officially recorded once in Dorset, which may possibly be due to the fact that the members of this genus are primarily night-flying ichneumons, which together with the various members of the Ophioninae subfamily, and certain braconids, are the core species of the 'Nocturnal Ichneumonoidea Recording Scheme'. I guess I was lucky to find one on the wing during the middle of the day.

New species added, March 25 (v.1)