Friday, July 2, 2010

Bees, Wasps and Aliens

Throughout my life, bees, wasps and I have had an uneasy relationship. The presence of stinging insects usually kicks in a healthy flight-or-fight response, one that only as an adult I have come to control.

My father’s honeybee hives sat at the edge of the woods, near the property line, facing a large expanse of “pasture” – a grassy field – that never saw a grazing animal. As a teen, it was my job to mow the ¼-acre plot.

Sitting atop the riding mower, I circled the field, spiraling towards the center. With no trees or bushes to obstruct their flight paths, the bees followed long low track lines across the grass. Sooner or later, one would collide with me, catching in my hair, unable to free itself. My immediate response was to bat at it, crushing it but not before it had inflicted several stings. (They say that honeybees sting only once, don’t believe it!) I lobbied hard for hazardous duty pay to no avail.

My current yard is too small to house honeybees but it is home to an interesting array of tenants. Wrens occupy the age-old birdhouse once more and robins fledged three babies in a hanging plant basket on the front porch. Bugs of all sorts are not strangers.

One evening, two large insects hovered over a maple log set on end in my driveway. These bugs were unlike anything I had ever seen. Six needle-thin legs supported the three-inch long bodies, dappled in brown and yellow. Each appeared to have a long black “tail” protruding more than three inches from its abdomen. This had the menacing look of a stinger to me. The sight caused that old knee-jerk reaction; I retreated behind the metallic safety of my SUV. The visitors, though, weren’t particularly interested in me I discovered. The focus of their attention was the log and with each passing minute, the feelings of uneasiness faded. From my initial vantage point about 10 feet away, I circled the log, moving closer and closer, observing them from every angle. Fascination and curiosity had gained the upper hand – these creatures were strange and new. What would they do next?

Amazingly, one began to “drill” a hole in the center of the log. The long tail appendage, actually composed of two parallel strands, looped back over the upraised abdomen. I could see a slight quivering, even as the insect itself remained motionless. The hole became deeper and deeper. Eventually, the end of the abdomen opened up like a clamshell and a third strand entered the hole – the ovipositor. This egg-laying apparatus guided the insect’s future offspring to their nesting spot.

These odd-looking visitors could easily have been cast as extras in an “Alien” movie. I had to find out what they were. Dr. Phil Pellitteri of the UW Madison Insect Diagnostic Lab answered my questions. He identified it as a species of Ichneumoid wasp. The body and ovipositor of the giant ichneumon wasp (Megarhyssa macrurus) may extend more than five inches. Great! A giant wasp with a stiletto stinger – a nightmare embodied. But, these insects do not sting and are considered beneficial. Their main prey is the pigeon tremex horntail (Tremex columba), another non-stinging wasp, a tree borer.

The horntail larvae develop in trees that are dying or recently dead. M. macrurus females drill into the bark with their ovipositors to find grubs of the host, paralyzing them before depositing an egg. In a parasitic relationship, the developing egg will then feed on the immobilized larva, lying dormant until the ichneumon adult emerges a year later.

Check out this Ichneumoid in action:

My fear of bees has receded with time; the gut reactions dulled. Bees and I have come to an understanding: most of the time, these insects will leave people alone unless provoked and I do my utmost to maintain that status quo. The Ichneumon wasps that visited took this awareness to another level. These alien-looking creatures, coupled with the horntail, participate in a complex natural history, one inextricably dependent upon the other. Knowledge has brought a deeper understanding and curiosity has taken the place of fear. One step in a life cycle dance played out before me, leading to a truer appreciation of Nature’s wondrous relationships.


Dave said...

Beautiful photograph and interesting reading - will be stopping by your blog more often now that I've discovered it!

timothysct said...

I really like your eye for the smaller world around us. The video of the Ichneumoid is great. What a strange creature.

Nature Blog Network