neighborhood naturalist CORVALLIS, OREGON — SUMMER 2016
Cuckoo Wasp article and photography by Lisa Millbank
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The spectacular colors of these tiny insects aren’t created by pigments; instead they are reflected from a stack of layers of cuticle. Researchers used a scanning electron microscope to photograph this stack of reflective layers, which measured a little over one micrometer in thickness. It’s not clear what purpose this brilliant coloration serves, but some scientists speculate that the primary purpose of the layers is merely These tiny wasps move frenetically as they scuttle around, to enhance the strength of the insect’s exoskeleton. And wiggling their antennae and inspecting every crevice and that strength is important for an insect that’s as bold and hole they encounter. They’re swift fliers, but prefer to run. daring as a female cuckoo wasp. Their constant searching behavior offers a little hint at their Cuckoo wasps can’t sting, so they defend themselves by bizarre lifestyle. curling up like pillbugs. A female cuckoo wasp in search of Their name gives a better clue: the cuckoo in cuckoo a host nest employs this defense in a surprisingly effective wasp refers to the brood parasitism of Old World cuckoos. way. If she’s attacked by the female bee or wasp whose nest Similarly, most of these wasps lay their eggs in the nests of she’s invading, she can roll up and protect her underside. other species of wasps, sawflies and bees. Cuckoo wasps Despite the efforts of the host bee or wasp to bite or sting aren’t totally unique among their relatives—there are also the cuckoo wasp, her hardened, pitted exoskeleton protects cuckoo bees and cuckoo bumblebees, which behave in similar ways. But cuckoo wasps are incredibly diverse, with her like a suit of armor. The nest owner soon finds that more than 3,000 known species in the family Chrysididae. the little invader is almost impervious to harm. In some Though information about western Oregon cuckoo wasps cases, the host female will grasp the cuckoo wasp and toss is lacking, there are probably a few dozen of these chrysidid her out of the nest. The cuckoo wasp can wait for the host female to leave her nest again and make another attempt species in our region. to lay an egg, or she may look for another nest. he first time I saw a cuckoo wasp, I thought it was a scrap of colored foil moving in the wind. It was almost too small to notice—about the size of a sunflower seed. A closer look revealed a shining, metallic insect, its entire body glittering blue-green as it scampered along the ground.
Neighborhood Naturalist, Summer 2016 v14 #2 • page 1