Darwin wasps

  Ichneumon wasps in the garden, menacing with their twitchy antennae and jerky movements, taking a break from parasitising insect larvae to satisfy their own energy needs.

Black Darwin wasp Ichneumon delicatorius

Yellow-striped Darwin wasp Ichneumon xanthorius feeding on nectar from lovage flowers. Its larvae develop parasitically inside the caterpillars of moths and butterflies.

 They are known as Darwin wasps because their gruesome life cycles played a role in undermining the great naturalist’s belief in a benevolent creator. “I cannot persuade myself,” he wrote, “that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their [larval stages] feeding within the living bodies of caterpillars.”

Sabre wasp

This is a sabre wasp aka giant ichneumon Rhyssa persuasoria.The last time I saw one of these was 56 years ago, when I tried unsuccessful to photograph it with the first camera I ever owned. I found this one in our conservatory a few days ago.

It's about three inches long, and half of that is accounted for by that long ovipositor (egg-laying tube), which is used for drilling into wood and laying eggs on insect grubs that are tunnelling, unseen, inside.

That sword-like tail is really a scabbard, protecting the ovipositor which is only about as thick as a horse hair but has a tip that's strengthened with accumulated metals, that allows it to drill through wood.

Rhyssa persuasoria finds its hidden prey with the help of those long antennae, which can detect the smell of frass that accumulates in the tunnel behind its prey as it chews its way through timber.

Once an egg has been laid and hatches, the ichneumon larva slowly eats its prey alive.

The usual host of Rhyssa is said to be the grub of the giant wood wasp aka giant horntail Urocerus gigas, but I suspect that it may also lay its eggs on other wood-boring insect larvae. 

There are several wood piles under the edges around our garden, specifically build for insects that breed in decaying wood, from trees that I have had to cut down over the years, so maybe that is what attracted this spectacular parasitoid to our garden.

Ichneumon wasp

Earlier this week we found this menacing-looking wasp high up in the Pennine moorlands near Alston in Cumbria. I wasn't too certain of its identity and thought it might be a digger wasp, but thanks to the kindness of Africa Gomez (check out her BugBlog site, it's excellent) I now know that it's a large ichneumon called Amblyteles armatorius, which lays its eggs on moth larvae, which the grubs then feed on.  Gruesome. Magnificent antennae, though. 

Apparently it usually spends most of its time on hogweed umbels and some sources say that it's a lowland species, so the fact that it was grounded and living at high altitude led me astray with the ID.

You can find more information on this insect by clicking here and here