March 03 – My Nature Journal

Metric Paper Wasp

Polistes metricus

I spotted these two Metric Paper Wasps crawling around on a concrete bridge railing.

Metric Paper Wasps reach their peak adult population around September but all the males and non-reproductive worker females die off when winter comes.

Only the queens (adult females capable of reproducing) live through the winter. They hide themselves away in various shelters referred to as “hibernacula” (singular “hibernaculum”). Hibernacula are places like the cracks in dead trees, the gaps under tree bark, and rock crevices that protect the wasps from temperature extremes and winter weather.

In the spring, these queens emerge from their hiding places and found new colonies. Metric Paper Wasps build umbrella-shaped nests that are open on the bottom and not wrapped in papery covering. The overwintered foundresses start to lay eggs as they build their nests. Eventually individual worker wasps (sterile females) develop and help with nest-building but the first workers don’t emerge from the cocoon until mid-July.

Given that today is only March 03, I suspect that this pair of Metric Wasps are reproductive females who emerged recently from their hibernacula and are preparing to found this year’s new colonies.

Unlike some of their vespid cousins like yellow jackets and hornets, Metric Paper Wasps have a reputation for being fairly calm and less apt to take offense to human encroachers. But the females can still sting and will do so when sufficiently provoked.

Thanks to the springtime efforts of the queens, many more Metric Paper Wasps will buzz around the landscape soon.

I, for one, will appreciate them only through a telephoto lens from a safe distance.