Yard Critter of the Week - Mason Wasp

Euodynerus megaera, the Mason Wasp.

Several Months ago, Steve put up this bee house for the native bees and wasps in our yard. Many of these critters are solitary and nest in dead plant stalks or in cavities created by woodpeckers. This bee house has both nesting type cavities for the discerning bee or wasp.

Mason bees and wasps will lay an egg with food and make a wall to create a chamber. They will fill the hollow cavity with larval chambers.

The Mason Bees will put pollen cakes in the chamber for the larvae to eat. You can see the yellow pollen on the hairs of this bee.

This is not a bee. There are two easy ways to determine if you are looking at a bee or a wasp. Wasps, unlike bees, have thin waists and little to no hair.

Unlike Mason Bees, Mason Wasps larvae consume living but paralyzed caterpillars. The female Mason Wasp lays her egg in the chamber. She then hunts for caterpillars and uses a potent venom to paralyze her prey. When the larvae hatch they feed on the living albeit paralyzed caterpillar. Due to the shorter developmental time of the male larvae, male eggs are usually placed near the opening of the cavity and female eggs are placed deeper within; therefore the female wasp is able control the gender of her offspring. Mason Wasps are considered beneficial because the caterpillars they collect are often pest species.

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You can find all of the Yard Critter posts listed here.

Thanks to guest blogger Patty Rehn. The words and images are hers.