Potter wasps and bee tongues

Potter wasp nest on the underside of a mexican plum leaf

I was reviewing some photos I took a couple of weeks ago at the Fort Worth Botanic Gardens when I stumbled upon this picture of a potter wasp nest. It had been tucked into the underside of a leaf on a Mexican plum tree, completely concealed from most perspectives.  I only noticed it because I had been examining curled leaves looking for caterpillars. Potter wasps (Euminidae) use mud to build these structures resembling clay pots (hence their name). After depositing her eggs, the female provisions them with caterpillars and other soft insects. 

Bee assassin eating a captured potter wasp

Potter wasps are quite common, and I often see them lurking in my garden hunting pest insects. Lately they’ve been hanging around my stricken-looking turk’s cap (Malvaviscus arboreus var. drummondii). I hope they get whatever’s been gnawing it. A few months ago I posted a picture of a bee assassin eating one of these artistically inclined insects on prairie parsley. Here’s a re-post of that image: 

Wasps are predatory, but they only hunt to feed their young. At adulthood they switch from a protein-rich insect diet to vegetarianism and flower nectar. Like most wasps, potter wasps have short tongues and can only reach the nectar on flowers with short corollas. Growing shallow flowers in the aster family is a good way to support populations of this beneficial insect.

Bombus pensylvanicus and her long tongue on some sort of white salvia

Conversely, many bumble bees have rather long tongues. The Bombus pensylvanicus worker, pictured at left, is a good example. She was very obliging and flew from flower to flower with her long tongue partially extended. While bumble bees also feed on asters, they have additional resources available to them that wasps are unable to extract. These long-corolla flowers that hide their nectar resources at the end of tube do so presumably to favor bees over other less effective pollinators. Lucky for the bees!