How to Identify Mason Wasps

Look for mason wasps in wood borings or burrows in dirt banks. Mason wasps also take over abandoned carpenter bee or ground bee nests.

Identify a mason wasp nest by looking for dead caterpillars or parts of caterpillars and cells separated with mud partitions in the nest. In addition to caterpillars, mason wasp nests may also contain other prey, such as cutworms, cabbage loopers, armyworms and beetle larvae.

Study the insect's physical characteristics. Mason wasps are approximately 20 mm (slightly less than 1 inch) long and black with bold, yellow-white stripes and markings. In some species, the markings can also be orange or red. Males have a yellowish pentagonal spot on their face.

Look for tunnels in the mortar between the bricks on the outside of your house or other structure. If you see winged insects resembling wasps inside or going into and out of these tunnels, the insects are likely mason wasps.

Spot mason wasps by their behavior. Unlike other kinds of wasps, hornets and yellow jackets, the mason wasp is a solitary insect, meaning it doesn't form colonies. Mason wasps are not aggressive and won't protect their nests.