Bug Spotlight!

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U.C. Riverside
Department of Entomology
Photo by: ERM

This is a closeup of the head and thorax of a Green Darner dragonfly (Anax junius). Dragonflies and their relatives, the damselflies, comprise the insect Order Odonata, all of which are characterized by their predatory aquatic immature stages ("naiads"), and distinctive, archaic types of wing venation, musculature and flight mechanism. Unlike most other insects, the wing muscles of dragonflies insert directly at the wing bases, which are hinged so that a small movement of the wing base downward lifts the wing itself upwards. Even though dragonflies cannot hover with this primitive mechanism (they can "cheat," though, with careful use of wind currents), damselflies can, and in both groups, the fore and hind wings are operated independently, which gives a degree of fine control and mobility not seen in other flying insects; not surprising given that these aerial predators have been terrorizing other airborne insects since before the dinosaurs - if they couldn't outmaneuver their prey, they would have gone extinct long ago. This flight mechanism also gives the lie to one of the well-promoted "mosquito repeller" scams (ALL mosquito repellers are scams, for various reasons). In this case, it's the type where the manufacturers claim that their device replicates the wingbeat frequency of a dragonfly (which supposedly scares the mosquitoes away): since dragonfly wing muscles insert directly, they do not HAVE a constant wingbeat frequency - their wingbeat speed can vary at random, like a bird, and not necessarily even in a rhythmic pattern.



2005 ERM-UC Riverside