The mystery of how spiders can fly for thousands of miles even in the complete absence of wind has finally been solved, researchers claim.

Arachnids travel through the air by releasing long fans of silk and floating away, in a process known as 'ballooning'.

The process that enables these wingless arthropods to float away when there is no wind and skies are overcast has intrigued scientists for hundreds of years.

The latest research shows arachnids can make use of electrostatic charges in the atmosphere to power their journeys.

This force, known as the e-field, can be detected by many insects and is used by honeybees to communicate with the hive.

Spider silk has long been known as an effective electric insulator, but until now, it wasn't thought spiders could detect and respond to e-fields in a similar way to bees.

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The mystery of how spiders can fly for thousands of miles even in the absence of wind may have an electrifying solution. Experts believe arachnids make use of charge in the atmosphere to power their journeys. Pictured - A ballooning spider a tiptoe stance on a daisy

Biologists from the University of Bristol found the answer lies in the Atmospheric Potential Gradient (APG), a global electric circuit that is always present in the atmosphere.

APGs and electric fields (e-field) surrounding all matter, and bumblebees can detect e-fields arising between themselves and flowers.

Researchers exposed Linyphiid spiders to lab-controlled e-fields that were equivalent to those found in the atmosphere.

They noticed that switching the e-field on and off caused the spider to move upwards or downwards respectively.

This proved that spiders can become airborne in the absence of wind when subjected to the e-field.

It also showed sensory hairs called trichobothria found on the surface of the spiders' exoskeletons move in response to electric fields.

This suggested spiders can feel the charge in the air using the same sensory hairs used to detect a breeze.

It seems likely a combination of both drag and atmospheric electric fields were at play in getting these insect aviators into the air.

This force, known as the e-field, can be detected by many insects and is used by honeybees to communicate with the hive. Pictured - A spider tiptoeing on a dandelion seed head

Lead researcher Dr Erica Morley, an expert in sensory biophysics, said: 'Many spiders balloon using multiple strands of silk that splay out in a fan-like shape, which suggests that there must be a repelling electrostatic force involved.

'Previously, drag forces from wind or thermals were thought responsible for this mode of dispersal.

'But we show that electric fields, at strengths found in the atmosphere, can trigger ballooning and provide lift in the absence of any air movement.

'This means that electric fields as well as drag could provide the forces needed for spider ballooning dispersal in nature.

'Many spiders balloon using multiple strands of silk that splay out in a fan-like shape, which suggests that there must be a repelling electrostatic force involved.'

HOW DO SPIDERS FLY? The aerodynamic capabilities of spiders have intrigued scientists for hundreds of years. Charles Darwin himself mused over how hundreds of the creatures managed to alight on the Beagle on a calm day out at sea and later take-off from the ship with great speeds on windless day. Scientists have attributed the flying behaviour of these wingless arthropods to 'ballooning', where spiders can be carried thousands of miles by releasing trails of silk that propel them up and out on the wind. However, the fact that ballooning has been observed when there is no wind to speak of, when skies are overcast and even in rainy conditions, begs the question - how do spiders take off with low levels of aerodynamic drag? Biologists from the University of Bristol believe the answer lies in the Atmospheric Potential Gradient (APG), a global electric circuit that is always present in the atmosphere. The strength of the APG varies as on a calm day with clear skies, when it may reach 100 volts per mertre On a stormy day or in the presence of charged clouds, the APG can soar to 10 kilovolts per metre. Researchers exposed Linyphiid spiders to lab-controlled e-fields that were equivalent to those found in the atmosphere They noticed that switching the e-field on and off caused the spider to move upwards or downwards respectively. This proved that spiders can become airborne in the absence of wind when subjected to electric fields. Advertisement

Spider silk has long been known as an effective electric insulator, but it wasn't known that they could detect and respond to e-fields in a similar way to bees - until now

Researchers exposed Linyphiid spiders to lab-controlled e-fields that were equivalent to those found in the atmosphere. They noticed that switching the e-field on and off caused the spider to move upwards or downwards respectively

This proved that spiders can become airborne in the absence of wind when subjected to electric fields

The findings have applications beyond the world of arthropods. Aerial dispersal is a crucial biological process for many caterpillars and spider-mites as well.

An improved understanding of the mechanisms behind dispersal are important for global ecology as they can lead to better descriptions of population dynamics, species distributions and ecological resilience.

There is, however, more work to be done. Dr Morley said: 'Current theories fail to predict patterns in spider ballooning using wind alone as the driver.

'Why is it that some days there are large numbers that take to the air, while other days no spiders will attempt to balloon at all?

'We wanted to find out whether there were other external forces as well as aerodynamic drag that could trigger ballooning and what sensory system they might use to detect this stimulus.'

'The next step will involve looking to see whether other animals also detect and use electric fields in ballooning.

'We also hope to carry out further investigations into the physical properties of ballooning silk and carry out ballooning studies in the field.'

The full findings of the study were published in the journal Current Biology.