A Couple o' Bruisers

A certain well-watered clump of goldenrod flowers at Halibut Point has provided a steady arena of insect activity through the recent arid months. Like an oasis in the savannah it has concentrated the insects for their subsistence, and consequently drawn predators on  the prowl. 

The goldenrod grows about 5 feet high. That's a convenient height for observing the bevy of nectarivores. Then a relatively enormous creature came crashing like a pinball through the flower canopy. It looked like an oversized bumblebee in black Kevlar with racing stripes.

Four-banded Stink Bug Wasp, Bicyrtes quadrifasciatus

I'd seen this fellow earlier in the month excavating a burrow on the Bay View Trail. It's a solitary sand wasp. Individual females lay their eggs in subterranean galleries provisioned with paralyzed prey to feed the growing larvae. She ends her part in the life cycle by sealing the tunnel.

The wasp almost never comes to rest. It searches high and low, inside and out of the vegetation, for food to bring back to its brood. Most desirable are nymphs (juveniles) of stink bugs and leaf-footed bugs. Adult wasps subsist primarily on flower nectar.

These behemoths of the branches frequented the goldenrod fairly briefly but another hefty hunter followed their forays in late August. The two species didn't seem to overlap, which may be the practical result of evolutionary design. It may also be due to the dominant size and aggressiveness of the newcomers.

Bald-faced Hornet, Dolichovespula maculata

The newcomers were Bald-faced Hornets, which bounced relentlessly through flowers and foliage scattering the smaller pollinators. Their fore and aft ends were boldly marked with what looked like war paint.

Bald-faced Hornet nest

The hornets‒actually large wasps closely related to Yellowjackets‒were on a similar nest-provisioning mission. They have constructed a papery, foot-ball sized, fiercely defended domicile with cooperative working assignments. They are considered Social Wasps. Each colony may number upwards of 300 individuals.

Flying through the goldenrod the Bald-faced Hornets seldom come to rest. They roam within the canopy inspecting the undersides of leaves and branches as well as flowers, evidently capturing a variety of insects and spiders to bring back to feed their larvae, along with the nectar that is also a mainstay of their diet as adults.

Black-shouldered Drone Fly, Eristalis dimidiata, yesterday

By mid-September the brawny carnivores have disappeared from the glade, leaving it a more tranquil place, though certainly not without hazards for emergent insects. For those of us who anticipate a long life it's hard to fathom that most insects spend only a small part of their lives‒days or weeks‒in a recognizable adult phase, if they happen to survive to maturity. That brief period is meant to ensure propagation and dispersal. It ends in death and the cycle of renewal through the usually much longer phases of dormancy, pupation, and juvenile growth.