In India, we have many unusual pests, and one is the so-called emerald cockroach wasp (Ampulex compressa). It looks beautiful even to those scared of insects, because it is metallic-iridescent in blue, green and purple colours. But what makes it interesting for me is its ways of breeding.
Why? Because pest controllers and this particular wasp share a common “enemy”: American Cockroaches (Periplaneta americana).
This wasp has a very efficient approach to cockroach control to us, using them as a food source. Many other animals do as well, but the way of the emerald cockroach wasp is almost unique.
First of all the wasp is much smaller than the cockroach: A female wasp is about 2 cm large, its prey the American cockroach is about 4cm. Looks like an uneven match? Wait and see.
The female hunts for cockroaches; once it finds one, it paralyzes the cockroach with a first sting. The second sting is much more precise and targeted at the area that controls the escape reflex in the cockroach’s brain. The cockroach is still able to walk, but simply sits and waits for whatever comes next. The wasp then bites off the cockroach’s antenna and uses the antenna like a leash to walk the much larger cockroach to a beforehand prepared burrow. The wasp then lays an egg on the cockroach and closes the burrow with small stones.
After the wasp’s larva hatches, it starts eating the paralyzed cockroach, at first outside the body and then from the inside, in a systematic manner in order not to kill the cockroach. That way, it keeps its food source alive and fresh. After the cockroach is totally consumed, the larva pupates. A new wasp hatches and the game begins all over again. Considering all the nasty surprises cockroaches have given me, its good to know that some wasps are giving them such a hard time.
Emerald cockroach wasps are never as common as their prey and I mostly encountered them in the country side, probably due to lesser disturbance by humans. Sounds like a deal to me, emerald cockroach wasps clean the country-side of cockroaches and we take care of the cities.