10 Facts About Emerald Cockroach Wasp

The Emerald Cockroach Wasp, scientifically named Ampulex compressa, is an insect species belonging to the family of Ampulicidae, and in the genus Ampulex. There are about 170 species in this genus, but the Emerald Wasp is one of the most widely known ones.

It naturally inhabits tropical regions where the temperatures are high year-round. You can find it in places such as Africa, South and Southeast Asia, and the Pacific Islands. They’re not a threat to humans, but they’re known to be scary parasitic predators. In this article, we’ll take a look at 10 interesting facts about this beautiful species.

1. They’re Also Affectionately Called “Jewel Wasps”

This wasp has a metallic blue-green body, just like bottle flies in a way. They’re known as jewel wasps for this reason. Their exoskeleton is very shiny, colorful, and attractive. Their legs are red, which further strikes a contrast with their exoskeleton, increasing the visual appeal even further. They’re quite beautiful in a way!

Jewel Wasps are about an inch in size, with females being bigger than males. They’re very similar in terms of appearance, in that both males and females are colorful. They have the same blue-green exoskeleton. I wouldn’t go as far as to call them cute or beautiful but they’re nice, in a way.

2. They’re Solitary Wasps

There are two categories of wasps out there. First, there’s the larger category of solitary wasps. Then, there are the lesser-known social wasps, which make only about 1000 of all the known wasp species. The Emerald Cockroach Wasp belongs to the former category. This means that Cockroach Wasps live, hunt, and raise their young all alone.

In comparison to solitary wasps, social wasps live in colonies. The colonies are centered around one queen. In some species, more than one queen wasp exists at any given time. In the colony, worker wasps hunt and gather food together.

The larvae born in the colony are raised by multiple worker wasps. In the case of the Emerald Cockroach Wasp, there’s obviously no queen. The wasps don’t congregate in colonies. Also, the larva is abandoned and left to feed by itself.

3. They Can Use Mind Control (On Cockroaches)

Many wasp species prey on cockroaches, but the Emerald Cockroach Wasp is quite unique. It could simply kill cockroaches but decides to do something far more sinister instead. With the help of a venom-soaked stinger, female Cockroach Wasps can perform meticulous brain surgery to alter cockroach behavior.

To take control over a cockroach, the female wasp sneaks up behind it and bites into its back to immobilize it. Then, she delivers the first venomous sting into one of the bug’s thoracic ganglia. It’s kind of like performing spinal anesthesia on a human.

The venom is injected into the bug’s upper back, leading to a quick but reversible paralysis of its front legs. Once paralyzed, the bug won’t put up a fight anymore.

Now, the female wasp has free reign to deliver the decisive blow (or sting). The wasp carefully searches for the exact spot to inject its venom into the bug’s brain. Once injected, the toxin alters the bug’s brain chemistry.

It completely shuts down the cockroach’s escape or self-preservation reflexes. As a result, the cockroach will no longer desire to avoid pain or fend for itself. But wait, it’s not over!

4. And They Walk Cockroaches on A Leash

Well, kind of. Remember what we’ve talked about in the previous point? Well, once the cockroach is completely zombified, the female wasp bites off its antennae to feed on the hemolymph pouring from inside (think of it as insect blood). That’s a sentence I never thought I’d put to paper but here I am.

Then, after she’s done feeding, the wasp has to move the cockroach to a safe location to feed it to its larvae (more on this in the next point). But the cockroach is too heavy to move around. The average Emerald Cockroach Wasp is only 22 millimeters long, while roaches can reach 35-41 millimeters— almost double the size!

So, the wasp has to make the roach walk by itself. I guess not having killed the bug comes in handy in this scenario. To lead the bug where she wants it, the female wasp pulls on its antennae stumps. The zombie bug then moves forward, as if being walked on a leash.

If that’s not downright terrifying and out of a horror movie, I don’t know what is. The zombie bug will eventually reach its destination and that’s when the wasp larvae will feed on it.

5. They Have Weird Reproductive Behavior

The horror story continues for our humble roach. Unique to many other wasp species, the Cockroach Wasp is a parasitoid. Its larvae need a host species to devour and extract nutrition from. That’s how they meet their growing needs. And you can now guess why this wasp is called the Emerald “Cockroach” Wasp.

For some reason, the preferred host is always a roach. So, after finding a male mate and breeding, the female wasp can fertilize multiple eggs with the sperm she saves in her ovaries. She flies around looking for the perfect roach for her babies. As we’ve already discussed in the last two points, the female wasp will first turn the cockroach into a zombie with her hypnotic sting.

Then, she’ll walk the roach on a leash to the perfect hiding spot, where she’ll lay her larvae. There will be two eggs for each cockroach she catches. She’ll lay these two eggs between the roach’s legs. After hatching, the larvae begin feeding on the bug, slowly building their way up into its abdominal cavity.

After eating its inner organs, the larvae enclose themselves in a cocoon. When they’re ready to emerge as adults, they will burst out of the cocoon, ripping through the old roach’s carcass at the same time. The entire feeding process takes around 13 days until the roach finally dies and the larvae enter the pupal stage inside its body.

6. The Larvae Produce Their Own Disinfectant

It’s long been a puzzling question for entomologists. How exactly can the larvae live inside a dying roach’s body? Cockroaches are known to carry lots of pathogens including antibiotic-resistant bacteria and dangerous microbes. Some of these microbes are even deadly for other insects, including growing larvae.

Such is the case for Serratia, a genus of bacteria consisting of 19 species. This bacterium can be found in healthy, diseased, and dead insects alike. They’re a natural part of the bug’s bacterial flora. It can be threatening to an insect’s health if ingested directly. So, how can these wasp larvae feed on rotting cockroach viscera without any issue?

Turns out, they’re capable of producing their disinfectant! This protects them against deadly bacterial infections. The larvae produce a light, clear liquid in their mouth. They spit these droplets out and smear them all over the roach’s inner walls.

According to Gudrun Herzner, a biologist at the University of Regensburg in Germany, there are two main molecules in this disinfectant. There are mellein and micromolide. When put to the test, these compounds stopped the proliferation of Serratia and many other dangerous bacteria.

7. Their Venom Might Help Future Parkinson’s Research

Parkinson’s disease is a degenerative disorder affecting the brain. It targets the brain neurons that produce dopamine. Besides dopamine’s role as a feel-good hormone, it also helps with nerve-cell signaling. When this signaling can’t happen, brain cells begin to slowly die off.

The venom produced by the Emerald Cockroach Wasp could offer a potential answer to the cell-signaling issue observed in Parkinson’s disease. It has recently been discovered that this wasp’s venom contains some unique peptides that could be affecting the dopamine pathway in cockroaches.

The process works similarly to how the dopamine pathway is affected in humans. However, unlike Parkinson’s disease, wasp venom has a transient effect on the brain. It only lasts for a few days, so the larvae have time to hatch and feed. Scientists believe that studying this mechanism could lead to a breakthrough in Parkinson’s treatment in the future.

8. We’ve Tried to Use Them as Natural Pest Control

The Emerald Cockroach Wasp isn’t known to sting humans. In fact, this insect is a hemolymph feeder. It subsists off of the blood-like substance of other insects, specifically cockroaches. Both the larvae and the adult wasps kill and feed on roaches. This makes them a great potential help for pest control.

And we’ve already tried hiring them for this position! Sadly, they aren’t very cooperative. This wasp is a common species in tropical regions of South and Southeast Asia, Africa, and the Pacific islands. In 1941, entomologist Francis Xavier Williams introduced this wasp to Hawaii as a means of natural pest control.

Sadly, human efforts of using Cockroach Wasps as pest control have failed. This wasp hunts on a very small scale, so it’s not enough to make a noticeable difference in the roach numbers. Second, these wasps are also extremely territorial. They won’t share their hunting grounds with other wasps, which makes them quite ineffective at eliminating roaches.

9. Males Jewel Wasps Don’t Have a Stinger

That’s right! Only female Cockroach Wasps have a stinger. And it makes sense when you think about it. Male wasps don’t need a stinger at all. After all, the female uses the stinger when hunting for a host for her larvae. Adult wasps don’t live as parasites inside roaches.

The only reason for Cockroach Wasps to use venom is when looking for a host for their larvae. So, since a male wasp can’t lay any eggs, they don’t need to be able to create a zombified host for larvae. Adult wasps, whether male or female, also don’t need their prey to be incapacitated. They can easily immobilize and bite into their prey as is, with the help of their sharp jaws.

10. Male Wasps Don’t Die After Reproduction

Social wasps have ruthless hierarchies within the colony. Furthermore, the sexual dimorphism between the sexes of the same species is a lot more evident. Soon after mating, a social male wasp will no longer be accepted back into the colony. To make matters worse, male wasps of such species are less well equipped to fend for themselves outside the colony.

As a result, they die soon after being kicked out. In comparison, Emerald Cockroach Wasps are solitary. They do not live in colonies, so each adult wasp has to be able to fend for itself. While male Cockroach Wasps don’t have a stinger, there aren’t many other differences between the sexes.

Males tend to be smaller than females, but are still strong and well-equipped to hunt and protect themselves. The male Cockroach Wasp has nothing to lose after mating. He can even mate multiple times throughout his life, without any repercussions.

Conclusion

Emerald Cockroach Wasps are as terrifying as they are beautiful. While they aren’t the only parasitic wasp species out there, they are quite unique. Whether it’s their beautiful emerald-green sheen, their amazing ability to mold the mind and behavior of other insects, or their grisly reproductive strategies, these wasps never cease to amaze.

Recently, they’ve caught our attention in more positive ways too. Their natural adaptations, including their venom and disinfectant, could unlock the door to great scientific breakthroughs in treating human diseases. And this is just the beginning! Clearly, these insects have a lot of interesting things to offer. What facts did you find most surprising?