Ditch Full of Distractions
Thursday, July 19, 2018
By MCHT Land Steward Kirk Gentalen
There are lots of ditches in St. George, but only one that we (the royal “we”) visit on a regular basis. I won’t give out the exact location (you know how protective ditch lovers are!), but let’s just say it’s a typical ditch—one that fills and flows after a good rain and becomes a collection of deepish puddles filled with some seriously mucky, algae water during drier times.
In other words, it gets kinda gross. It’s a smallish ditch, no more than a foot across at its widest, but we don’t hold that against it—there is too much life there to be distracted by volume!
The fliest of the flies
When it’s warm and sunny, the air above the ditchy water can be full of fly activity—a fly-lovers paradise, if you will. And while there are several species of flies to entertain a visitor, there is only one that we actively search for and hope for a glimpse of. That is the “Phantom Crane Fly” (PCF).
These aren’t your typical Crane Flies (of the Family Tipulidae), the ones you might mistake for huge mosquitoes when found in your house (fortunately, they don’t bite). Nope, these dudes are part of their own family (Ptychopteridae – Phantom Crane Fly family) and fly with a style and grace all their own.
“These dudes fly with a style and grace all their own.”
A thing of beauty
Our local species of Phantom Crane Fly (Bittacomorpha clavipes) is quite the sight. Their heads and thorax are minuscule and unassuming, their abdomens are thin and measure .5 inch (if that). On their backs are a pair of shrunken wings, which are essentially vestigial organs that have become useless over time (similar to leg bones found in snakes)
What stands out about PCFs at first sight, are their long, thin, black and white banded legs. At the tip of each leg are swollen feet (tarsi) loaded with tiny holes called trachea.
The trachea is typically used for respiration in insects but PCFs don’t breathe through their feet (that would be weird). Instead, they use the trachea to catch the tiniest of wind currents and breezes as they drift along. An insect with wings that flies by its feet!? For maximum efficiency and flying potential PCFs fly with their six legs extended and spread wide, giving them it an appearance like a flying snowflake or spider web.
Cruising the ditch
In flight, this leg arrangement gives PCFs a look similar to filter feeders in the tide pools, but these adults are not thinking about food. They actually lay their eggs in those algae pools, and as larvae, their offspring feed on detritus in the muck before morphing into non-eating adults.
So there is no chasing after prey or catching of food with those big legs. Instead, PCFs are looking to mate. Hot action at the ditch!
The black and white pattern on the legs is perfect camouflage for shady habitats sprinkled with sunlight. Disappearing in and out of the shadows in flight gives these flies a “phantom” appearance and makes following them tricky, to say the least. (Warning: attempts to take photos turn into lessons of patience and focus.)
Spend some time with a ditch and you’ll realize that you aren’t alone in hunting PCFs (and the other flies in the area). A handful of Green Frogs also call the ditch home. (Warning: nothing teaches a lesson in patience like watching a cold-blooded predator sitting in wait.)
Daily fluctuations in PCF numbers makes one wonder how many PCFs have made their way through the ditch frog’s digestive systems. PCFs are towards the bottom of the food chain for sure. So it goes…
“It can be hard to pick what to watch when spending time in the ditch!”
What do blackbirds have to do with ditches?
On this particular visit to the ditch, blackbirds have a bad habit of announcing my presence with loud alarm calls (I wasn’t even close to them, I swear!). As I try to convince the blackbirds that I mean no harm (probably would be better if I just zipped it instead of talking to them) Swamp Sparrows start to belt out their buzzy song in the nearby cattail habitat. Swamp sparrows have a special spot in my heart and have long been my favorite sparrow (for reasons I can’t remember) so ignoring those is not an option.
It’s a party!
Meanwhile, butterflies and dragonflies zip around the grasses and clovers. A river otter even crosses the ditch before plunging into a nearby waterway with a big splash.
A Broad-winged Hawk catches a thermal above us and attracts the Blackbirds’ attention. The hawk is promptly “escorted” away from the wetlands by the male of the pair.
Phew. It can be hard to pick what to watch when spending time in the ditch (and beyond)!
In this case, the visit to the ditch was inspired by visions of Phantom Crane Flies. And like almost all adventures, the plethora of “side” activity demands observation and adds to the experience. We really aren’t there just to see the PCFs or the ditch – even though that would be more than satisfying. We’re there to see the habitat and learn about the “neighborhood.” All distractions are welcome in these cases!
A version of this story originally appeared in Kirk’s “Nature Bummin’” column in The St. George Dragon.