Blue Mud Dauber Wasp Found in Barnegat, NJ

While sitting on her patio, a homeowner in Barnegat, NJ noticed a blue, metallic, odd-looking (at least to her!) wasp burrowing in the sand between her patio blocks. These wasps have a blue and black sheen and a narrow waist between their thorax and abdomen. As with most people, she thought that wasps lived in nests, so she did not know what to make of this lone burrowing insect with a big intimidating stinger. As it turned out, this was a blue mud dauber, which is a solitary wasp. Unlike social wasps like paper wasps, yellow jackets, and hornets, solitary wasps do not live in colonies. Instead, the female wasp will build and supply her nest individually. These wasps are not territorial like social wasps and tend to keep to themselves. However, these solitary wasps often make unsightly mud nests or burrow tunnels in the ground. Although they have stingers, they are not aggressive to people and rarely use them.  

The Blue Mud Wasp is affectionately known as the Black Widow Killer. This venomous spider has a deadly enemy of its own, the blue mud wasp, which is most famous for its predation of black widows. Although these wasps feed on nectar and is a pollinator, these wasps need to feed their developing larvae high-protein foods. For whatever reason, they have an affinity for black widows, immobilizing them with their stinger and then converting them into larvae food.  

This occasional invader is considered to be a beneficial insect since they reduce the number of some pest insects, not the least of which is the black widow spider. Also, these wasps are not likely to sting. However, if they happen to start building unsightly mud nests on your home, especially in high traffic areas, or are causing damage by their burrowing activity, the infestation needs to be treated. Here, I treated the wasp burrows with a residual application that will stop this occasional invader from doing more damage by digging up her patio.