Intrigued to see a large, shiny black wasp that lays eggs in trees in your nearby park or garden? This is probably the giant ichneumon wasp, and it is perhaps one of the most fascinating creatures among us. Let’s learn more about this gentle giant.
The giant ichneumon wasps are strikingly large insects found across the wooden areas of North America.
These parasitic wasps lay eggs in the larvae of a pigeon trimix horntail, which grows in dead tree trunks.
Intrigued to learn more about these wasps and how they lay eggs in trees? Continue reading this article.
What Are They?
The long-tailed giant ichneumon, scientifically known as Megarhyssa macrurus, belongs to the wasp species of the insect order group Hymenoptera.
A typical giant ichneumon is 2 inches long (about the size of your index finger) with a thin body and long abdomen. It has a reddish-brown body with black and yellow-orange stripes and transparent wings.
The female giant ichneumon is distinctly known for its 5-inch long ovipositor, which it uses to insert eggs in the potential host.
The male does not have an ovipositor since it’s the female who lays eggs on the larva. So, the female wasp has a longer body as compared to her male counterpart.
Why Do They Lay Eggs In Trees?
The giant ichneumon wasp is a parasitoid in nature; it needs a host to lay eggs in order to complete its life cycle.
The larvae of a giant ichneumon feed on the larvae of a pigeon horntail wasp, who develops in a rotting tree trunk.
Thus, you need a dead tree with a pigeon horntail larva to attract a female giant ichneumon wasp to lay eggs.
How Do They Know Where To Lay Their Eggs?
There are two explanations for how the female giant ichneumon wasp locates the pigeon horntail larva. We have discussed them both below.
The first explanation is that the giant ichneumon female probably uses her sense of smell to locate the host.
Once she is assured about the presence of the pigeon horntail larva in the tree, she uses her long ovipositor to drill the bark and insert her eggs next to the larva.
The other understanding is that the female wasp possibly uses her antennae to pick up the vibration of the larva’s location in the tree.
She then drills through the tree bark to find and paralyze the larva and lay her first egg on its body. The minute the egg hatches, the ichneumon larva starts feeding on the immobilized wood wasp larva.
How Do They Lay Their Eggs?
Since we have learned how the female wasp knows where to lay the eggs, we must discuss how they do it.
The female ichneumon is a natural predator and finds the host through her sense of smell or picks up its vibration using her antennae.
Once she locates the host, her 5-inch long ovipositor starts drilling through the tree bark until it reaches the pigeon horntail larva.
It takes about 3 to 4 hours for her to get to the larva and lay a long, skinny egg on its body.
Once she inserts the egg, the mother wasp’s job is finished. The minute her egg hatches, the larva starts eating its host’s body.
It takes several weeks for the larva to finish its meal. When it finally reaches the pupal stage, the larva consumes the remaining part of the host’s body and starts chewing its way out of the tree.
What Kind of Trees Do They Prefer?
Horntail wasps generally attack trees that are dead or in the process of dying. Ichneumon wasps lay their eggs on these larvae, so where they go, the wasps go too.
If the tree has a possibility of reversing its decline, these wood-boring insects will leave it alone.
Thus, if a tree near you has become a shelter for horntail wasps, it is a sign that it is dead.
Frequently Asked Questions
Do ichneumon wasps sting humans?
Ichneumon wasps are not interested in interacting with human beings. They don’t even have a stinger, so it is simply not possible to sting us.
The female has a large ovipositor which can’t sting us, and the males don’t even have that.
They share a beneficial relationship with us since they naturally help in pest control. They are wasp pollinators and can travel up to 2000ft to disperse pollen and find horntail nests.
Are parasitoid wasps harmful to humans?
Parasitoid wasps are not harmful to humans. In fact, they are quite beneficial to human beings.
They act as a biological control agent and help in eliminating pest populations, especially in agricultural areas.
Many of these wasps control crickets, grasshoppers, caterpillars, spiders, aphids, thrips and other such insects that can ruin your precious plants.
What does an ichneumon look like?
A typical ichneumon wasp is about 2 inches long and has a reddish-brown body with multi-colored stripes.
The female has about 4 to 5-inch long ovipositor and, thus, is bigger than the male, who does not have the appendage.
Both are bigger than other commonly observed wasps but are extremely thin.
Can parasitoid wasps lay eggs in humans?
There is one parasitoid wasp that lays eggs in humans – the German wasp! The larvae feed on human skin, which can result in a painful rash or swelling.
Apart from this one wasp, most other parasitoid wasps only focus only on insects and small invertebrates.
Wrap Up
We hope this article helped you learn more about this beautiful wasp that lays eggs in trees.
When Charles Darwin first encountered this species, he remarked that he could not believe in a God who would design creatures with the intent that they would feed on live caterpillars.
While the description is apt, ichneumon wasps are much more than just parasitoids – they are our friends, gentle pollinators, and also devoted parents to their young.
If you liked what you read, please do give us a shoutout!
3 Comments. Leave new
I just found this bug in a tree in East Tennessee. Are they normally found this far south?
We found a Giant ichneumon on the front porch. He is black and kinda purple in the light. Long tail and looks like a wasp.
i saw one of these sitting on my back porch screen door i took a picture or it from the inside when i tried to get a picture from the outside it flew a way but in the picture i saw yellow and brown and maroonish colors on its back and to my surprise i saw and very long black thing hanging from its back wonce i noticed that i ran back inside.