“Is that a stinger?” our dad asked as he looked up at the bizarre creature we found on our gazebo one summer in North Dakota. The insect looked like a wasp, and it had an alarming 4-inch (10-cm) spike on the end of its abdomen.
But fortunately for all of us, the menacing spike on the back of the insect was not a stinger. It was the ovipositor of a giant ichneumon.
There are around 25,000 species of ichneumon wasps in the world. That means that there are more species of ichneumon wasps than there are of both mammals and birds put together! They can be found all over the world except in Antarctica.
Although ichneumon wasps, especially the giant ichneumon, look rather scary, most species are not harmful to people. In fact, they are actually quite beneficial! Ichneumon wasps are parasitic wasps that prey on many species of larvae that can be harmful to crops. Some species even attack spiders. The ichneumon wasp is an exceptional pest control agent! The word ichneumon comes from a Greek word that means “tracker footstep.” This name refers to the ichneumon wasp’s practice of hunting down insects to parasitize.
How exactly do ichneumon wasps prey on these pests? It all goes back to that long ovipositor. A female ichneumon wasp will hunt down certain kinds of caterpillars or spiders and pass an egg through its ovipositor onto—or even into—the animal. When the egg hatches, the ichneumon wasp larva feeds on the host, eventually killing it.
Sometimes a female ichneumon wasp will inject venom into the host along with the egg. There are two types of venom: idiobiont and koinobiont. An insect injected with idiobiont venom will not be able to move or grow, while those affected with koinobiont venom can still grow.
The giant ichneumon targets pigeon tremex horntail larvae and other similar species. Using her antennae, the female wasp feels for vibrations in the trunk of a tree. When she finds a likely spot in the tree, she bores her ovipositor into the wood and places an egg in a horntail’s tunnel. After the ichneumon larva hatches, it will parasitize a horntail larva.
Adult ichneumon wasps eat plant sap and nectar, as well as a variety of other things. In some species, the female eats insects, sucking their juices.
There are actually a few species of ichneumon wasps that can use their ovipositors for stinging. So don’t touch, just in case! Most kinds of ichneumons that sting people are larger than other species and have a short ovipositor. Only the females of these species can sting.
What are some differences between ichneumon wasps and other kinds of wasps? As you already know, most wasps can give a painful sting. But as I said, most ichneumon wasps cannot sting, even though some have a long nasty-looking ovipositor. Another difference between ichneumons and other wasps has to do with their antennae. Ichneumons have sixteen segments in their antennae, which is several more than other wasps.
Now, see what fun critters you can find in your backyard. When you find one, do research and learn what it is and how it lives. You never know what spectacular bug or plant you may find. We found a fantastic insect right outside our door.