PicoBlog

Most people are wary of wasps, and with good reason. You would be hard pressed to find someone who hasn’t had at least one encounter with the social wasps in Ireland that has ended in a painful sting.

That said, those stinging, social wasps make up just 0.25% of the wasp biodiversity in Ireland. Yes, you read that correct, one quarter of one percent. This, of course, means that there are nearly three thousand other wasps all around us at varying times throughout the year. And most of these never make our radar.

One particular group of wasps that most of us never encounter are the night wasps. These tend to be seen mostly by moth enthusiasts who find them semi-regularly in their overnight moth traps. For this reason, they are very under-recorded in this country.

So, it’s my great pleasure to introduce you to Netelia cristata (Thomson, 1888)

I recently had occasion to accidentally catch one of these special wasps while out doing some biological recording. It was getting late in the evening and I decided to head back to my car, which was a 15 minute walk away. It was warm and humid and, despite my insect repellent, I was attracting the attention of far too many horseflies. I took to swinging my net around my body and head in a regular sweeping pattern to catch them and rid myself of their nuisance. Every so often, I would stop, look into the net for anything of interest, and let everything else go before continuing on my journey.

During one of these inspections, I spotted the above female wasp in my net, and my excitement was uncontrollable. It was my first time seeing one in real life. I figured it was either Ophion sp. or Netelia sp. based on my limited knowledge.

The word that crops up regularly when describing these genera of wasps is “testaceous”. I had to look that up! It is an entomological term meaning a dull, brick red colour. You can see why from the photo above.

To put their family tree in context they are:

• Family: Ichneumonidae

• Subfamily: Tryphoninae

• Tribe: Phytodietini

• Genus: Netelia

• Subgenus: Bessobates

Each level of this family tree brings with it certain characteristics, which are probably too technical to go into here, but suffice it to say, this wasp operates in darker hours and uses the larvae (caterpillars) of Noctuidae moths as hosts.

Operating during the night brings its own issues, of course. Darkness brings with it navigation challenges and this wasp has ocelli which are clearly much larger than those which would be seen in its sister Hymenoptera. The ocelli are, of course, simple photoreceptors that help insects and invertebrates use light for simple navigation purposes and can help flying insects control their pitch and roll (to use pilot’s parlance).

The wasp is very unlikely to use sight as a means to find host prey for its eggs. The long antennae contain chemoreceptors that allow the wasp to identify its focus host by smell instead. The wasps will crawl over foliage normally frequented by their hosts, and sniff them out from closer quarters.

While some Ichneumon wasps have long or very long ovipositors, allowing them to lay their eggs on buried, hidden or burrowed larvae in plants or wood, the fact that this wasp lays its eggs directly on the caterpillars is perhaps evident from the length of its ovipositor.

And, to bring us full circle, back to the start. The night wasps, in particular Ophion and Netelia contain some of the very small number of Ichneumon wasp species which can inflict a painful sting on humans. Indeed, Netelia are some of the very few Tryphoninae who have been observed to subdue the host caterpillar temporarily with venom before laying the egg although not necessarily this species.

A stunningly beautiful and completely accidental discovery turned into an amazing voyage of discovery for me as I chose to dig deeper into the life of this “night wasp”. I hope you enjoyed the fruit of those labours.

Brian

ncG1vNJzZmidnqm8tLzAnJxnq6WXwLWtwqRlnKedZL1ww8Csp6xlpJ2utXnGqGSbrZ2leqq6jK2fnmWenrSpwA%3D%3D