Clap and Fling

Insects are ubiquitious throughout the world. Most of us are familiar with winged insects such as butterflies and bees. Insect flight is an interesting topic from a biomechanics perspective. Unlike birds, most insects (with some eceptions, such as dragonflies and others) do not have flight muscles attached to their wings. Instead, their flight muscles oscillate their thorax, which in turn makes the wings move. Furthermore, they beat their wings at a very high speed. The aerodynamics of insect flight are also very interesting. Larger insects are able to fly by creating a leading edge vortex. This method does not work in the smallest insect fliers. Such insects include the thrips and chalcid wasps, some of which have wingspans as small as 1 mm. These insects have unusual wing structures, as can be seen in this image:

The solid part of the wing is rather small and narrow, with many large bristles projecting from the solid part of the wing. Insects such as thrips do not create a leading edge vortex; instead, they fly using the “clap and fling” method. This method is common amongst insects who fly in the intermediate Reynolds number regime, $1\leq \mathrm{Re} \leq 100$.