Uninvited but welcome guests: mason wasps
A lot has been written about the mason bee.
This powerhouse of pollination has become the poster child for the plight of backyard bugs. It has inspired countless articles and spawned a cottage industry of bee houses, books and other supplies to help create inviting and safe habitats for this helpful insect.
Several months ago, I wrote about my own trial and error efforts in supporting our native bees, including how I was successful in moving my mason bees when my wife and I moved a few years ago. You can imagine my concern when I recently noticed what I thought was a predator buzzing around my beloved mason bees’ house.
It caught my eye because it was early September and far too late in the season for mason bees, which emerge with spring blossoms, to still be active. As I got closer, I could see it wasn’t any species of bee that I’d seen before. It had a narrow mid-section, shiny wings and black and white striping. I immediately became concerned it was preying on my developing bees.
It was a wasp.
A lot of people have the notion that the only good wasp is a dead one. While I was perhaps one of those people at one time in my life, I have long since given up that thinking. However, there are certain species of wasps known to break into mason bee chambers and prey upon the larvae. So, I did have some concern for my mason bees as I approached.
Noticing its coloring, I typed, “black and white wasp nest mason bees,” and a picture popped up that matched the little insect in front of me: a mason wasp.
Mason wasps are part of a subfamily of wasps, Eumeninae, that build homes out of mud and other materials. This family includes potter wasps, which build structures under or on the ground, and mud daubers, which build homes or tubes on walls and trees. There are nearly 3,000 species of potter/mason wasps in the world.
The black and white wasp I spotted is a four toothed mason wasp (Monobia quadridens) and can be found living nearly everywhere in eastern North America. Its close relative (Pachodynerus) is red and black. It can be found in our region but is more prevalent in the southeastern United States. Once you notice them, they are tough to miss.
The female wasp I saw was not a threat to my bees. Like mason bees, mason wasps have evolved to build nests in holes. As a solitary wasp, it builds chambers within the hole to lay its eggs. Similar to mason bees, mason wasps will not pass up an empty nesting tube when one is provided.
Mason wasps lay eggs twice each season. Rather than piling up pollen for their young to eat, mason wasps hunt other insects. A mother wasp paralyzes and stashes away cutworms and other small caterpillars for their young to feed upon. They place several caterpillars in each egg chamber. Adult wasps contribute to pollination by entering flowers to drink nectar. Their overall impact in controlling damaging caterpillars and feeding activities make them a beneficial wasp for our gardens.
A word of caution: mason wasps can deliver a painful sting if handled. They are rather docile otherwise and do not seem concerned with people. In fact, when I first spotted this wasp, in a protective knee-jerk reaction, I picked up my mason bee house. After my quick internet search dispelled my fears, I replaced it. The wasp simply ignored me, took a moment to locate her nesting tube and continued her work.
If you happen to see these black and white visitors around your own mason bee homes or buzzing around your flowers and vegetables, you can rest easy. They are busy helping you and your plants. Consider rolling out the red carpet for these uninvited, but beneficial, guests.
If you are interested in learning more about mason wasps or other pollinators, more information is available at https://extension.psu.edu/insects-pests-and-diseases/pollinators/identification-and-biology. Learn more about building a mason bee home of your own at https://extension.psu.edu/programs/master-gardener/counties/lawrence/how-to-build-your-own-mason-bee-house
If you have gardening questions, you can email fayettemg@psu.edu and a Master Gardener will respond. You can also find us on Facebook at https://extension.psu.edu/programs/master-gardener/counties/fayette where we share gardening news and tips and announce webinars and special events.