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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Scary Potter – Potter wasps, Eumeninae


Potter wasps eat nectar and pollen when not throwing pots. 


While trimming weeds around a flower bed, I noticed a small earthenware vessel attached to the side of a stone. Having seen these before attached to walls, twigs, and leaves; I knew I had discovered a real delight, the brood chamber or “pot” of a potter wasp. We caught a glimpse of the potter wasp as one of the bright yellow and black, somewhat scary visitors at the goldenrod flower in the last episode of Bug of the Week - “Beautiful in yellow and black.”

What wonders lie within this primitive diminutive piece of earthenware? 

The adult potter wasp obtains nutrients from the nectar and pollen of flowers. But when they are not on the hunt for a snack, they are busy constructing homes for their young. This home is the curious pot from which the potter wasp gets its name. This diminutive master of masonry gathers clay and soil particles in moist areas and transports them back the construction site like the side of a stone. Layer by layer she carefully molds the mud into a tiny hollow vessel. This requires many trips to the mud puddle.

Green and brown caterpillars fill the small pot. 

When the pot is nearly finished, but before it is sealed, the potter wasp completes two important tasks. First, she provisions the pot with enough food to support the growth and development of her youngster that will grow inside the pot. In the case of the potter wasp in my garden, the larder consisted of at least five rather small caterpillars in shades of green and brown. Other potter wasps fill their pots with beetles or spiders that will be food for their young. Upon finding a caterpillar the potter wasp delivers a paralyzing but non-lethal sting, and then carries the victim back to the pot where it is interred. When the pot is fully stocked with fresh meat, the potter wasp deposits an egg on the unfortunate victims.

The legless larvae of the potter wasp has a bounty of caterpillars to eat.

To keep her youngster safe, the potter wasp gathers more mud and seals the chamber completely. After a few days the egg hatches into a small legless larva. Surrounded by food and protected from most of its enemies inside the pot, the larva grows and develops as it eats the nutritious caterpillars. After completing its development, the larva forms a pupa and transforms from a legless mass of flesh into a spectacular wasp. With powerful jaws the wasp breaks open its earthen nursery, frees itself, and emerges to find a mate and eat. It then undertakes the tasks of gathering mud, capturing caterpillars, and building a little pot for its own offspring. I have read that these tiny pots may have inspired pottery designs used by Native Americans. Keep a sharp lookout for these small wonders.