There's nothing that ruins a picnic faster than a downpour – or a swarm of uninvited flies joining the festival.
Now experts have found a simple solution to this all-too-familiar disease: sit on a plaid picnic blanket.
Checkered and striped patterns create an optical illusion in the eyes of a horsefly that blinds them and prevents them from landing and biting, according to the new study.
Experts have found that sitting on a plaid picnic blanket can repel flies
The discovery came after Bristol University scientists discovered the mechanism behind the apparent disorienting effects of crosswalks on flies.
The study's authors say the exact mechanism remains unknown, but finding verified patterns that also blind flies proves that it is not the "aperture effect".
This would only apply if the flies were only distracted by stripes.
The "aperture effect" is an optical illusion in which moving stripes, e.g. B. on rotating barber pole signs, give the impression that the pole is moving upwards.
The discovery came after Bristol University scientists discovered the mechanism behind the apparent disorienting effects of crosswalks on flies
Lead author Martin How from the University of Bristol said: "Picnickers with checkered tablecloths can now just rest!"
He told MailOnline: "Wearing patterned clothing would also protect us from being bitten."
The question of why zebras striped has puzzled biologists for over 150 years, and study author Tim Caro has worked over the past decade to discredit many theories.
Professor Caro has explored theories such as their use as a camouflage from predators, a cooling mechanism, and their role in social interactions.
Stripes confusing predators are another common explanation, but Caro says they're also flawed when looking at the scientific data.
Instead, increasing evidence suggests that it is parasitic flies that are mistaken for the zebra's distinctive pattern. The aim of this new study was to find out how.
The mystery of why zebras have their distinctive stripes has puzzled researchers for over a century
Professor How said, “Movable stripes, like those on the rotating barber bar signs outside the barbershop, appear to move at right angles to the bar rather than in its true direction, so the bar appears to move up rather than around its axis.
“We wanted to find out whether this illusion also takes place in the eyes of biting flies when they land on striped hosts.
& # 39; As a fly approaches a landing surface, it adapts its speed to the rate at which the surface is expanding beyond its sight, allowing a slowed and controlled landing.
& # 39; Stripes could, however, disrupt this "optical flow" through the aperture effect, leading the fly to believe that the landing area is further away than reality. This means that the fly cannot slow down or land successfully. & # 39;
The results published in Proceedings of the Royal Society B increasingly show that parasitic pests are confused by the characteristic structure of the zebra.
The study only applied to horseflies, and the researchers didn't look at whether striped and checkered patterns could repel other insects like wasps.
In Africa, blood-sucking horse flies carry diseases that can seriously damage zebras, causing the beasts to develop stripes that helped protect the zebras.
PATTERN AS A SHAPE OF INSECT REPELLENT
One hypothesis of how stripes on a zebra keep insects at bay is that they disrupt optical flow patterns.
These are needed by flying insects to make controlled landings.
This can be done by disturbing the radial symmetry of the optical flow via the aperture effect or by misregistration of repeated features – the stripes with evenly spacing.
In a study, different mechanisms were tested by recording and reconstructing the flight behavior of horses with differently patterned carpets.
They found that flies avoided landing, flew nearby faster, and didn't get as close to striped and plaid carpets as gray compared to gray.
"Our observations that flies avoid checked patterns in a similar way to stripes refute the hypothesis that stripes interfere with optical flow via the aperture effect," said the Bristol University team.
You said this required critically parallel stripe patterns.
This means that there must be another mechanism at play between flies and horses.
A series of experiments supported the theory by limiting the possible mechanism that resulted in a confused landing between brakes.
Previously, the same team from Bristol University showed that the flies would approach horses in striped carpets as often as they did plain carpets. But they couldn't land or slow down.
Essentially, disoriented strips the pests – causing them to collide with the skin or buzz in a different direction.
The researchers covered domestic horses with various carpets and recorded the flight of flies that tried to land. 3D reconstructions showed that horizontal and vertical stripes as well as checked patterns were equally effective at repelling flies.
Verified carpets provide visual input that is free of aperture effects, the team explained, saying the flies would theoretically likely land without difficulty.
However, flies had real problems – they barely landed on plaid or striped carpets – suggesting that stripes aren't unique when it comes to deterring horseflies.
"These exciting studies not only bring us closer to understanding one of the most famous and photogenic species in the world, but are of great interest to farmers trying to reduce the damage caused by fly bites," said Caro.
He said it would also be of interest to horse clothing companies who could create new clothing designed to distract horse flies.
Protecting animals from flies in the spring before they are seen on the farm is critical to avoid major economic losses in production.
Zebras are pretty good at not being bitten by flies – not just by their stripes.
They use their tails to beat them away and when flies land they don't stay long because zebras move around a lot.
The results were published in the journal Proceedings of the Royal Society B.
ZEBRA STRIPES: A number of theories have attempted to answer why they exist
There are several possible explanations as to why zebras have black and white stripes, but a definitive answer remains to be found.
There are a number of theories that contain small variations on the same central idea and have been broken down into the following main categories.
- Apparent enlargement
- Visibility in poor light conditions
- Movable strips can blind predators
- Social benefits
- Fitness ad
- Protection against tsetse flies.
The research areas of camouflage and social benefits have many nuanced theories.
For example, social benefits cover many minor variances, including:
- Zebras recognize each other by their stripes
- This is especially important for visual communication between mothers and their foals
- Stripes can also be visual markers for group bonding or direct grooming companions to specific parts of the body.
Anti-predation is also a wide-ranging area, including camouflage and various aspects of visual confusion.
These explanations have been thoroughly discussed and criticized by scientists, but they have concluded that most of these hypotheses are experimentally unsubstantiated.
As a result, the exact cause of the stripes in the zebra is unknown.