The Wasp That Kills Black Widows

Blue Mud Dauber Wasps

Black widow spiders are probably the scariest pests living in Michigan. They’re surprisingly common, highly venomous, and they’ll live anywhere they want. Luckily, they have natural predators; where life finds a way to create something terrifying like the black widow, it also finds a way to balance it out.

That’s where the blue mud wasp comes in. Believe it or not, blue mud wasps hunt and eat black widow spiders. A lot. In fact, they’re considered one of the black widow’s primary predators. And they’re just as if not more common than the black widows here in Michigan! Here’s the lowdown on blue mud wasps, including how they hunt black widows and why.

What is the Blue Mud Wasp?

The blue mud wasp (Chalybion californicum) or is a species of mud dauber wasp; it is commonly known as the “blue mud dauber.” The “mud dauber” name references the fact that the wasps build their small nests in mud. The blue mud wasp’s name references its body’s distinctive, metallic blue-black sheen. Male blue mud wasps are around ⅜ to ½ inches long; females are between ¾ to ⅞ inches long.

Like other mud daubers, blue mud wasps are solitary. They steal their mud nests from other mud dauber species, replacing the original larvae with their own and tending the nest as if they’d built it themselves. Blue wasp larvae resemble most maggots: they’re around an inch long, cream-colored, legless, and defenseless. Adult wasps tend to the larvae by dropping food into the nest continuously.

Do Blue Mud Wasps Really Kill Black Widow Spiders?

Yes! Believe it or not, the food blue mud wasps bring back to their young… is usually black widows! While the adults themselves tend to drink plant nectar, black widow spiders provide an excellent source of protein for the growing larvae.

Blue mud wasps follow a very clever routine to capture their prey. First, they seek out and tap on a black widow’s spider web. Feeling the vibrations of would-be prey, the black widow comes out – and the blue mud wasp strikes! The wasp uses a specialized stinger to immobilize the black widow, rendering it defenseless so its larvae can eat it. Blue mud wasps will actually “stock” their nests with paralyzed spiders even before they produce offspring. Blue mud wasps also target other spider species, but they primarily eat black widows.

Where Do Blue Mud Wasps Live?

The blue mud wasp is common throughout North America, from southern Canada to northern Mexico. Blue mud wasps can live in a wide variety of environments. They’re particularly common near sources of water (and therefore mud). Because blue mud wasps steal nests instead of making their own, they tend to live where other dauber species do.

They’ll also build paralyzed spiders into these nests by constructing mud “cells” around them. If you’ve ever noticed a wasp flying around with a mud ball in its mandibles, you may have caught one in the act! Nests look like circular or oval-shaped mud balls. You may also notice exit holes where fully grown wasps emerge.

Are Blue Mud Wasps Dangerous?

Not unless you’re a spider! Blue mud wasps and other mud daubers are considerably less aggressive than other wasp families. Unlike social wasps, daubers will not aggressively defend their nest or territory. Even if you accidentally stumble upon a dauber’s nest, it’s unlikely that they’ll chase you off. Blue mud wasps can sting humans, but it’s very, very rare. The only time a blue mud wasp might sting you is if you deliberately antagonize it.

Where You’ll Find Blue Mud Wasps

Blue mud wasps are usually pretty easy to spot, even from a distance. Look for an iridescent blue shine, often on or near flowers. The dauber’s blue sheen frequently catches the light. You could also look for their nests, which could be either on the ground or affixed to a wall. Nests may be somewhat difficult to find, especially if they’re new; wasps rarely build nests out in the open. You’re more likely to find them on, near, or under a form of cover.

Keep Your Home or Business Safe With Griffin Pest Solutions

Nature is a system of checks and balances – even where the black widow is concerned. Just because venomous spiders may scare us half to death doesn’t mean they get to break the rules. There’s something oddly comforting about the notion that even black widows have something to watch out for.

That being said, you can’t exactly rely on the blue mud wasp. It’s just doing its own thing, after all; it’s not watching out for you. If these wasps were effective pest control on their own, you wouldn’t have a problem in the first place. If you have a spider (or wasp!) concern, depend on Griffin Pest Solutions instead. We have the solution to your problem.

Give us a call to get started with a free estimate.