Ever seen this intimidating critter and wondered what it was? It’s an Ensign Wasp! But don’t worry, it won’t sting you. It will, however, lay it’s eggs inside the egg cases of cockroaches. It’s a beneficial parasitic wasp!


Ensign Wasp Tiny (1)


The US pest control market in 2020 is valued at a whopping $16.2 billion. Pests are not only a nuisance, but a pest infestation puts your family at risk. These tiny unwelcomed guests are known to be disease carriers, and some can even cause structural damage to your home.

However, not all insects are pests. By definition, a pest is an animal or insect that dangerous to humans, plants, animals, or causes a nuisance and is destructive. Some insects, such as the ensign wasp, are beneficial to have around.

Read on to learn more about the ensign wasp and find out how they are beneficial to you.

What is an Ensign Wasp?

If you have seen an insect in your house that resembles a fly but isn't one, it's probably an ensign wasp. Also known as hatchet wasps, these oddly shaped insects are black in color and have triangular and flag-like abdomens. Their abdomens move up and down, making it look like a flag that's being signaled, hence the name ensign wasp.

They belong in the family Evaniida and feed on nectar and honey dew deposited on leaves by aphids. Adults can reach ¾ inches long.

How are Ensign Wasps Beneficial?

Unlike other wasps or bees, ensign wasps are not known to sting or harm humans or pets in any way. However, this is not why you should refrain from squashing an ensign wasp. As hatchet wasps reproduce, they help in controlling cockroach infestations.

Roaches are one of the most versatile pests that are hard to eradicate fully. This is because, even after exterminating live roaches, their eggs can survive and hatch months later. This is where ensign wasps come in. When a female hatchet wasp wants to lay eggs, it looks for cockroach egg cases, referred to as ootheca, to lay her eggs inside.

When ensign wasp eggs hatch, the larva will eat the cockroach eggs within the case. The larva will remain inside and only emerge as an adult after pupating.

What Does the Presence of an Ensign Wasp Signify?

Ensign wasps often feed around areas where they can breed. The presence of one indicates that there may be cockroach egg cases or even adult roaches within your house.  So, once you spot an ensign wasp, allow it to do free roach extermination for you. However, you should also take action. Search for ootheca and other signs of roaches in crevices. Ensign wasps can help prevent future infestations.