Tuesday, October 2, 2012

The Pigeon and the Giant

This story begins early on October 28, 2011, when a mass of cold air moving across the mid-Atlantic states met up with a low-pressure area originating from the Carolina coast. The fury of the collision brought wild winds and, the next day, a momentous October snow. The silver maple trees on Cherokee street, still bearing a full load of green and yellow leaves, became heavily laden with nearly 7 inches of heavy white wetness.

Or, maybe it can be traced much further back to the historical causes of the extreme weather events that are more commonplace than in years past, whatever they might be.

Or, maybe it has nothing to do with the freak October storm, but simply springs from the natural decline of living things. After all, the silver maples on Cherokee Street are “of a certain age.”

We can speculate all day long, but that does not change one fact: branches snapped and fell with the sound of gunshots all afternoon and evening of October 29th. On Sunday morning the ground around the houses on Cherokee Street was liberally layered with large limbs.

It just so happens that the Pigeon Tremex, a non-stinging wasp known as a horntail, is particularly fond of weakened or recently deceased limbs of certain trees, including the silver maple. It is likely that they saw, or smelled, or sensed, bounty in this disaster.

Or, possibly the horntail wasps were a contributing factor of the wreckage, exacerbating the weakness of the limbs that ended up littering the ground on that Sunday morning. Because their cream colored grubs live buried out of my sight within the wood, and because I did not inspect the trees for carcasses of female horntail wasps (which have been known to die midway through the act of depositing their eggs into the trunk), or look for the telltale small round holes through which the adults exit, I cannot say for certain that the strange-looking wasps with spines pointing out of their hind ends were present at all. But, as you will soon see, I have reason to suspect that they were.

Yes, I will get to the point. On Sunday, 11 months almost to the day following the rare October snowstorm that may (or may not) have factored in to the decline of the silver maples on Cherokee Street and the subsequent assumed presence of pigeon tremex horntails, I felt the slightest brush, like from a feather, as I was preparing my houseplants for the indoors. Clinging to the side of a pot was a fearsome insect. Actually it was more curious than ferocious, with its dainty waist, and a 3-inch needle projecting from its posterior. Being the savvy researcher that I am, I did a google search for “wasp with long tail.” Wasp was my best guess at the insect’s identity—based not so much on its form as on its hornet-like, “get-one-inch-closer-and-I-will-cause-you-pain” stance. I was right. It was a Giant Ichneumon wasp.

You’re probably wondering how the pieces of this story tie together: an October snow; weak-limbed silver maple trees; a specialized wasp that is drawn only to certain trees that can host a certain white rot fungus, and only when the trees are in a certain state of decline; and a wasp with a 3-inch needle-like “tail.”

As specialized as the pigeon tremex horntail is, the giant ichneumon is even more so. In order to survive, its larvae must eat the horntail grubs that are eating the decaying wood. Amazingly, the adult female giant ichneumon can sense what’s happening under the bark of the tree. She walks along the dead or dying limbs, antennae outstretched like divining rods, until she detects the location of a horntail grub beneath the bark. Then she puts her “tail,” which is actually an ovipositor sheathed by two filaments, to work. Bracing her abdomen with the protective sheaths, she drills through the bark into the tunnel of the horntail larva with her threadlike ovipositor, paralyzes the grub with a sting, and deposits her eggs into it. After a time, the horntail is no more. The following summer, the giant ichneumon emerges in its place. A female ichneumon is greeted by a crowd of eager males—they are able to somehow sense where and when she will make her debut. In no time at all she is out roaming the logs, instinctively, magically (or so it seems to us) finding just what she needs to find.  

We are all integrated in the natural cycles of life and death, decay and regeneration, and the lives of pigeons and giants might intersect from time to time with ours. Their bizarre and somewhat threatening appearances make them stand out from the crowd. We might label the giants “beneficial” parasitic wasps, and the pigeons “pests.” Doing so suggests that we believe it is all about us. Or it could just be that words are not up to the job of characterizing tangential, or parallel, relationships.

Trees age. Limbs crash to the ground. Seen and unseen creatures fulfill their specialized functions. The story continues … indefinitely. There are no happy endings. Or happy endings abound. Take your pick.    

1 comment:

  1. I had one of these stuck in the weather stripping of my windshield. Thanks to this post I was able to ID the insect. Thank you.