Another Kind of Air Show

Two Sundays ago, on the thirteenth, Sue and I did something unusual for us: we left the house, and not only did we leave the house, we did something that was strictly for fun! We weren’t procuring food or dry goods, or running errands, or driving anyone to an appointment. We just drove north of town, across the river, to see the weekend’s air show more closely.

We’d been hearing and seeing the planes pretty well from our yard; we’re only about three blocks from the Capitol, and thus the river, and the airfield is just north of the river. Some of the planes even flew over our house. As they do.

We didn’t want to pay or anything, and we didn’t need to see any patriotic signage or whatever. We just parked in a gravel lot between US 54 and the airstrip and looked up.

It was okay.

Sue always waves when she sees a small plane flying fairly low. It’s leftover from her childhood, flying on Island Airline’s Ford Trimotor to visit her grandma Bower on North Bass Island in Lake Erie.

When the air show seemed to be winding down, we took a brief, leisurely walk on the Katy Trail nearby.

The Katy Trail is a fun way to be out in nature, sort of. Most of the plants are what you’d call weeds. Many are nonnative. I mean, look, they’re growing along some old traintracks. And in many places, the trail goes by agricultural fields (perpetual soil disturbance), and the whole shebang is in bottomlands: moisture.

But although the vegetation is weedy, the growth is rank, and there are many nonnative and invasive plants, it is fun to see the insects that are drawn to all the jungley vegetation.

Here are a few little “friends” I saw along the trail, putting on their own brilliant air show.

First, a dolichopodid, or longlegged fly. I have no idea of the genus, much less the species. But it was so pretty, like a tiny jewel-bird, perched on a leaf. On close inspection, I could see it was dining daintily on a gnat.

I usually take a whole bunch of pictures, hoping that at least one turns out okay. In the process, I accidentally jostled the leaf, causing the fly to launch upward a few inches, but then it lit again near where it had been. It hopped a few times before it settled more comfortably. But for a few seconds, it looked like it was performing some kind of interpretive dance, its long legs hopping and landing, hopping and landing.

So that’s the first little air show.

The second was a surprise for me: I’m usually not fooled by flies that mimic wasps, but boy, this was a good one! This was a fly, but as it crept around on several big clusters of goldenrod, I thought surely it was a yellowjacket.

Now, yellowjackets are very common this time of year—they’re drawn to juicy, rotting fallen fruits, to whatever sweet things are in outdoor trash containers, and to untended, open soda cans. Be careful when you sip!

But, yeah, no! This lovely insect is a type of syrphid, or flower fly. Just like the longlegged fly, it is a true fly (family Diptera); it is no more harmful than a housefly. Bees, ants, and wasps are in a completely different family.

This species is the eastern hornet fly, Spilomyia longicornis. It’s simply fantastic, even compared to other syrphids.

The mimicry is brilliant. Look at the crisp black and yellow bands, and even the smooth surface sheen of the body. The swirly, mottled eyes disrupt their huge size that would otherwise help us see this as a true fly. Also, notice how the middle and hind pairs of legs are yellow, while the forelegs are black—at a glance, they give the impression of a wasp’s long, busy antennae, downplaying the little V of tiny antennae characteristic of flies. Finally, the fly’s two wings are two-toned, giving the impression of a wasp's four slightly overlapping wings.

For that matter, the timing is brilliant: this is the peak time for yellowjacket activity and numbers, and here are these flies, making the most of their resemblance.

As I ponder this, what really gets me is that this mimicry evolved and functions to fool animals incapable of logic. And this camouflage will certainly fool most people, whether they’ve taken any biology or not.

You’d think that black and yellow bands, and “buzz-buzz,” should be enough, but the mimicry of this insect goes above and beyond. It disrupts many of the anatomical hallmarks of a true fly: the two wings, the short antennae, the enormous eyes, as well as the body shape and color pattern. These are the kind of characters you’d learn in “Zool. 350: Invertebrate Zool.”

I actually did not see this insect fly; it was so addicted to the goldenrod’s nectar and pollen, it just crept from flowerhead to flowerhead, pigging out. But this spiffy flier was certainly a highlight of my own personal air show that day.

And yeah, this is a great time of year to look for cool insects on goldenrods. Bring your camera.