Saturday, July 10, 2010

Adirondack Natives: Sweaty Days and Sweat Bees

The big news item this week is the heat. Hazy, hot and humid days envelop us in their muggy warmth, driving most of us indoors to sit by fans or luxuriate in the cool blasts from air conditioners. How fortunate we are to live where these options exist. Still, I needed fodder for today’s column, so I grabbed the camera and went stalking subject matter in the butterfly garden. I lucked out with a close encounter with a sweat bee.

Not much was moving in the garden – even the wildlife seemed to be seeking shelter from the heat. But one bright metallic green bee was busily foraging on a milkweed flower and I was able to capture her image.

Many nature photographers are drawn to metallic-colored insects: they are just so photogenic. And, as odd as it seems, there are a lot of them. Bees, flies, beetles – it seems that almost every major group of insects has at least one metallic representative.

My little find turned out to be Augochlora pura, one of the Halicids, or sweat bees. Sweat bees get their name from the fact that they are attracted to sweaty people – they crave the salt that is on our damp skin. But we should exhibit caution around them, for they also pack a powerful sting.

One theory for the existence of the metallic coloration is that it serves as a warning that these insects are dangerous, at least in the case of these bees. When the sun hits their bodies, they glitter and sparkle with greens, blues and coppers. For most insects, the metallic coloration is a result of structure. The hard exoskeleton is made of chitin, a colorless substance that gives the insect support, kind of like a corset. Cracks, fissures, scales or hairs on the chitin refract any light hitting it, bouncing it back in a spectrum of colors.

Usually found along wooded edges, A. pura is noted for its choice of nesting material. Most Halicids nest in the ground, but A. pura prefers soft, decaying wood for building her nest cells.

A typical day for A. pura goes something like this: morning arrives and it is time to forage for pollen. Pollen collecting continues until the afternoon, when the female bundles the pollen into a ball and places it in a nest cell. She lays her egg and caps the cell. During the night, she excavates another cell for tomorrow’s egg and awaits the dawn, when it is time to forage once more.

During the course of a summer, two or three generations of A. pura emerge into the world. Come fall, however, things change. Females that were lucky enough to mate crawl into wooden chambers in the base of decaying logs and there they wait for spring. The males die off. In the spring, the females lay their eggs, and the cycle begins again.

Augochlora pura is a solitary bee, and one of our important native pollinators. I’ve mentioned the plight of wild pollinators before, but it never hurts to repeat an important subject. As more and more land is converted from its natural wild state into monocultures of self-pollinating crops (corn, wheat, rice, soybeans), monocultures called lawns, or just plain pavement and buildings, our native bees find less and less food, and thus produce fewer and fewer young.

With the decline in honey bee populations, it is really in our own selfish best interest to do what we can to encourage native bee populations. Without them, the foods that we eat that are not self-pollinating (most fruits and vegetables) will no longer be available.

I encourage everyone to take the time to get to know some of our native bees, and to make the back yard a more bee-friendly place. This can be done by letting parts of our lawns “go wild,” eliminating local ordinances that require all lawns to be cut and managed to within an inch of their lives, and planting native vegetation before we plant non-natives. It doesn’t take much, but it can make a world of difference to our small flighted brethren.

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Ellen Rathbone

Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





2 Responses

  1. Woodswalker says:
  2. Ellen Rathbone says:

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