Blinded by the light: Insects could be left disoriented by bright lights, research finds

One of the abiding mysteries of science is why flies gravitate towards artificial light.

But experts believe they may have solved the puzzle – and it might even leave you feeling sorry for the insects.

For years, scientists have believed that bugs may be interpreting artificial light as an escape route or that insects are blinded by the light source.

Now, it appears that they could be getting vertigo from bright lights and ending up completely disoriented.

A team from Imperial College London used high speed infrared cameras to track insects’ flight, both in their natural environment and in a lab.

They examined a range of insects including moths, dragonflies and fruit flies.

Now, it appears that they could be getting vertigo from bright lights and ending up completely disoriented

Analysis revealed that insects appear to mistake bright light for the direction of ‘up’.

During the daytime this makes flying easy, as they keep their backs tilted towards the bright sky and can hold a steady flight path correctly oriented with the horizon.

But artificial light makes them fly erratically, causing the creatures to continually correct their flight path – resulting in insect vertigo and producing what we see as an attraction to artificial light.

Author Samuel Fabian said: ‘We think the weird flight is due to insects confusing the light with the direction of “up”.

‘For 370 million years insects have been flying around, the sky has almost always been brighter than the ground.

‘Insects, amongst other animals including fish, use the brightest region as an indicator of where the sky is and thus which way is up.

‘Knowing which way is up is critical for flight as you must direct flight forces to cancel out acceleration due to gravity.

‘However, we’ve started spoiling this general rule by creating bright lights at night.

‘Insects think these bright patches are the sky and tilt their backs towards them to redirect their flight forces to where they think gravity should be.

Author Samuel Fabian said: ‘For 370 million years insects have been flying around, the sky has almost always been brighter than the ground. However, we’ve started spoiling this general rule by creating bright lights at night’

A team from Imperial College London used high speed infrared cameras to track insects’ flight, both in their natural environment and in a lab

‘Unfortunately, they’re wrong about where gravity is and this imbalance leads them in all sorts of weird flight paths.

‘The most obvious example of this is when insects fly directly over lights, they flip themselves upside down and plummet to the ground.

‘Insects can’t accurately measure gravity directly while in the air as they’re pulling all sorts of accelerations that feel the same as gravity and are indistinguishable.

‘Using the direction of light is a beautifully simple way of solving this problem. That is until someone starts sticking big streetlights everywhere at night.’

The findings were published in the journal Nature Communications.