I’ve been too busy writing reports lately to post anything here, and for the rest of this month I will be doing fieldwork in Maine, with little or no free time or internet access. So I thought I’d dash off a little something right now, in the gap between work and dinner.
This March, after several consecutive 80-degree days, I decided it was time to get started in the garden. As I was digging around in the raised beds, I found this papery cocoon, 2 cm long:
It had a similar texture to the cocoon of a black and yellow mud dauber (Sceliphron caementarium), but was a little different (and not found in a mud nest), so I figured it belonged to some related kind of wasp. I threw it into a container, covered it with some soil, and continued gardening. Sitting there among all my other bags and jars, I quickly forgot what was in this unlabeled container of soil, until two months later when I noticed this wasp crawling around in it:
This is a wasp in the genus Ammophila, which like the black and yellow mud dauber belongs the family Sphecidae, known as the thread-waisted wasps (I think you can see why). Ammophila species, like many wasps, dig holes in sandy soil and place at the bottom a paralyzed prey item, on which they lay an egg. Various digging wasps use flies, beetles, spiders, grasshoppers, cicadas, or other prey items; Ammophila species use caterpillars. Unlike, say, cicada killers (Sphecius spp.), Ammophila adults do not leave conspicuous piles of soil next to their burrow entrances, because they carefully carry away the soil as they excavate.
Ammophila adults are often seen on flowers, and apparently the only one I had photographed previously was this one, which had fallen prey to a well-camouflaged crab spider (Thomisidae) while visiting some daisy fleabane (Erigeron):
When I set the newly emerged wasp on the stone walkway in front of the house to photograph it, it began wandering around and soon discovered the white splatter of a robin dropping, which, as so many other insects do, it found delicious.