Wildlife Research, Monitoring & Mentoring

Think Like a Fly

Dioctria hyalipennis

To be successful at hunting or fishing, the saying goes, you need to learn to think like your prey. The same is true of insect study: by learning to imagine the world from an insect’s perspective, you greatly increase your chances of finding something interesting to watch or photograph.

A case in point would be the unexpected importance to insects of sunlit leaves. From the human perspective, a cluster of leaves in bright sunlight rarely registers as anything significant. But to many insects, a sunny leaf can represent a highly attractive micro-habitat. Perched on such a leaf, an insect can warm itself up to operating temperature. And it can survey the surroundings for prey, mates, or competitors. An elevated perch provides a broad field of view or even an opportunity to intercept airborne chemical cues, like the pheromones (scent hormones) that many insects release to attract potential mates.

Robber fly basking on a leaf.

A small robber fly, Dioctria hyalipennis, scans for prey from its perch on a sunlit goldenrod leaf.

When I’m bug-hunting in a wooded environment, then, I keep part of my attention focused on the top surfaces of leaves, especially ones illuminated by the sun. Even when very little seems to be active, this strategy usually lets me find something interesting to observe. Robber flies, in particular, love to use leaves as perches where they can wait for prey to fly past. These highly visual insects are easy to disturb and often disappear completely when you flush them. But by constantly scanning likely robber fly perches, I can sometimes spot one of these predatory insects before I’ve come close enough to disturb it.

And many species of tiny, predatory long-legged flies — members of the family Dolichopodidae — are inordinately fond of hunting on the top surfaces of sun-warmed leaves. Presumably their logic is the same as mine: if you want to find insects in a woodland, remember that sunlit leaves are popular places to perch, rest, observe, and forage!

Reddish, iridescent fly perches on a leaf.

Many tiny long-legged flies (the family Dolichopodidae) love to forage on the top surfaces of leaves. This one is probably in the genus Condylostylus.

<a href="https://biodiversityworksmv.org/author/matt-pelikan/" target="_self">Matt Pelikan</a>

Matt Pelikan

Position

A year-rounder on the Vineyard since 1997, my academic background is in literature, but I’ve studied and written about wildlife from birds to beetles. I hope you’ll join me in exploring the natural diversity of this incomparable place!

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