Sunday, June 24, 2018

The Chalcid Wasp: Not Your Everyday Pollinator


The diversity of nature is astounding. Even in the small corner of the world that is the Sycamore Greenway--102 acres--there is an amazing number of flowers, birds, insects, and all other variety of life to be seen if one simply pauses to look.

At a walking pace, much of the insect life is invisible. You may see a Monarch fluttering busily through the basins, or hear a chunky bumblebee buzzing around the red clover along the trail. But there is so much more! Stop and look--really look--at the cluster of black-eyed Susan there just a few feet away. How many different kind of bees do you see? And is that a wasp?

What about the wild quinine? Each patch along the way seems to be fairly deserted. But then there is one particular plant that is crazy with activity: bees, syrphid flies, ants, and...dear god, what in the name of all that is holy is THAT?!?!

It looks like nothing so much as an alien shrunk down to miniature size: large mantis-like eyes astride a pair of charming antennae; a rounded and segmented shield on the back of its thorax, and what is up with those crazy hind legs? Chunky thighs curled over dainty, hair-thin feet that seem too small to carry the burden of those legs.

It lingered long enough to get a decent shot for later identification, and then we went our separate ways. At home, Google was an abject failure (there are, apparently, thousands of weird-looking bugs with big hind legs). Plan B--paging through an insect guide--turned up a close hit. The subject appeared to be a Chalcid wasp.

Chalcid wasp (Conura sp.) on wild quinine. Adults may feed on
nectar and pollen; their young have more macabre tastes.
The lifestyle of the Chalcid wasp is as horrific* as its appearance would suggest. They are parasitoids, laying their eggs in their hosts--either the pupae of butterflies and moths or larvae of flies--which then hatch and devour their hosts, killing them in the process. The strangely-large femurs may help the females grasp and maneuver the pupa or larva in which she intends to lay her eggs. Though unfortunate for the host insects, this process is another demonstration of the incredible diversity of life and methods of survival**, and is also useful in keeping populations of pest insects in check.

* I know, it is actually kind of cute from this angle. But it was a jarring sight creeping into few after dozens of adorable, pollen-dusted bees.
** One blog post mentioned the theological conundrum posed by parasitoids like Chalcid wasps in a God-designed world. Fun to imagine this little wasp and its kin being the subject of philosophical debate!


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