Go! . . . Ball! . . .

Today I set off for the wooded pond on a utilitarian endeavor, that is to procure some benthic invertebrates as food for a dragonfly nymph I’m rearing. On my way I walked by the St Olaf ball fields where the college men’s team was practicing. One group repeated an infielder’s drill where a coach shouts “Go!” and two players sprint away, then “Ball!” and the players look back for the thrown baseball and one calls it and makes the catch without breaking stride. For most of the time I’m out I hear these calls repeated. “Go! … Ball! . . . . Go! … Ball!”

At the pond, the first scoop through the shallow water yielded dozens of Phantom Midge larvae or Chaoborus (also widely known as Glassworms). A few more scoops yielded more of the same, but eventually a few other creatures are observed as well: several leeches, a diving beetle, snails, and a damselfly nymph. I collected about a dozen Chaoborus and turned for home.

My first encounter with Chaoborus occurred while in college during a visit to the Trout Lake Research Station in northern Wisconsin. One night, I volunteered to help some biologists sample larval perch. This involved going out well after dark and using a push-net in front of a boat. In addition to the nocturnally active larval perch the nets captured masses of wriggling, clear jelly, a concentration of thousands of Chaoborus. I’d sampled this same lake during the day on numerous occasions and had never seen this insect. I was amazed.

One of the world’s most common insects and yet one of the least observed due to its diurnal migration from sediments during daylight to the surface at night. Right away I admired the scientific name, how the word “chaos” was bundled into it. And I was mesmerized many times watching the springy way the larvae moved, how they would be absolutely still then suddenly coil into something like the letter “C” then just as suddenly straighten back into the long lowercase letter “l” and glide away.

Seven years ago, in 2010, I made the following observation at the same pond on nearly the same date: “I stopped at the edge of the pond to have a look at the welcome sight of open water. After walking and covering a lot of ground, it takes a few minutes for the body and the eyes to adjust to being still. Eventually I begin to see movement in the shallow water, snails, zooplankton, a few small water beetles. And then a procession of phantom midge larvae appear, of course they were there all along, their slender transparent bodies are nearly invisible until betrayed by the pairs of air sacs that look like black segments of an orange located at the front and back of their bodies. They move in a most surprising manner, gliding like tiny pike then spastically they double themselves up and unfold, launching themselves like an arrow on another glide.”
— Rice County Odonata Journal: Volume Three (Thistlewords Press, 2013)

Posted on 31 de março de 2017, 02:51 AM by scottking