It turns out insects have pretty good eyesight after all

Ever wondered why bugs trapped in your home manage to dodge your rolled-up newspaper so easily, despite supposedly having terrible eyesight?

Well, flies and other insects have better vision than we first thought, a new study from biologists at the University of Sheffield has found.

Scientists had assumed that flies had pretty blurry vision because of their compound net-like eyes.

The human eye
Parts of the human eye have photoreceptors that are 500 times more densely packed than a fruit fly’s (John Stillwell/PA)

Human eyes have a lens that changes shape and a number of densely packed light sensitive cells called photoreceptors underneath that, making for high resolution vision.

In contrast, the photoreceptors in fly eyes are more sparse, which up until now lead us to believe that they couldn’t see very well.

In collaboration with scientists from Cambridge, Beijing and Lisbon, researchers designed their own special microscope to film behind fly eyes, and watch how these photoreceptors react to light.

A fly head seen through an electron microscope
This is probably why flies can dodge your swats so easily (HeitiPaves/Getty)

They found that these light sensitive cells move automatically in and out of focus at very high speeds, and can detect the fluctuating light levels caused by constant tiny movements of the head and eyes.

This means fly photoreceptors are better adapted to picking up light and they can probably see small moving objects (like a swat swinging in their direction) quite easily.

Mikko Juusola, Professor of Systems Neuroscience at the University of Sheffield and lead author of the study, said: “We have demonstrated that fruit flies have much better vision than scientists have believed for the past 100 years.”

The research was published in the journal eLife.


 

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