The artistry of solitary wasps
While doing some gardening last summer, I noticed a tiny mud structure attached to the branch of a serviceberry tree. First of all, I was impressed with myself that I even saw it, and secondly, that I knew what it was — that tiny structure was the work of the female potter wasp.
Most of us are familiar with social wasps, and a close encounter can often result in one or more painful stings. By social, I mean those that live in colonies such as paper wasps, yellow jackets and bald-faced hornets.
However, there are more species of solitary than social wasps, and many of them are fascinating and also beneficial. Such is the case with the potter wasp.
The female potter wasp is 3/8 inch to 3/4 inch long, the male slightly smaller. They are shiny black with yellow or ivory markings. The thorax is connected to the abdomen by a long, thin “waist.” They are found in eastern North America as far south as Texas.
Two to three generations can be produced in a single year due to a short life cycle. Eggs from a fall mating can overwinter emerging in the spring.
It is the mud pot, about the size of a marble, constructed by the female for each egg that gives them their name.
The female builds her structures on twigs, vines and the outside of buildings. She gathers water, mixes it with soil then transports it to her nesting site. Once the structure is complete, she “provisions” the brood chamber with several larvae and / or caterpillars. Each morsel is stung to paralyze it, keeping it alive but in place. She lays an egg and seals the top of the chamber with more mud. The new adult will chew a round hole in the side of the chamber when it is ready to emerge.
The pipe organ mud dauber wasp is another solitary species that also constructs its brood chamber with mud. The nest is a series of linear tubes, and each tube can house several eggs. Nests are often found on the side of structures.
Females stock the tubes with paralyzed spiders, lay an egg then seal it with mud. The process is repeated until the tube is filled. Like the potter wasp, adults chew holes in the side of their chambers to exit.
Both species of wasps are beneficial in that they eliminate garden pests or pesky spiders when they provide for their offspring. In addition to that, adults feed on nectar, so they function as pollinators.
Solitary wasps are not aggressive and should be admired for their truly interesting life cycles. For more on potter wasps, go to http://go.osu.edu/potterwasp and to read about other solitary wasps and bees go to: http://go.osu.edu/solitarywasps.
Steffen is an Ohio State University Mahoning County Extension Master Gardener volunteer.