Benjamin Radford, LiveScience Contributor
Date: 23 January 2013 Time: 05:34 PM ET

According to some estimates, crop circles appear every week somewhere around the world. The strange circles and patterns appear mysteriously overnight in farmers’ fields, provoking puzzlement, delight, and intrigue for both locals and the news media. The circles are mostly found in the United Kingdom, but have spread to dozens of countries around the world in past decades. But who — or what — is making them?

Milk Hill Crop Circle
This massive 780-foot (238 meters) crop circle appeared in 2001 in the remote area of Milk Hill in Wiltshire, England. The elaborate design is composed of 409 circles that form a pattern called a double, or six-sided, triskelion, which is a motif consisting of three interlocking spirals.
CREDIT: Handy Marks | public domain

Early claims of crop circles

Many people believe that crop circles have been reported for centuries, a claim repeated in many books and websites devoted to the mystery. Their primary piece of evidence is a woodcut from 1678 that appears to show a field of oat stalks laid out in a circle. Some take this to be a first-hand eyewitness account of a crop circle, but a little historical investigation shows otherwise.

mowing devil
A woodcut pamphlet that some claim represents an early crop circle.

The woodcut was actually used to illustrate what in folklore is called a “mowing devil” legend, in which an English farmer told a worker with whom he was feuding that he “would rather pay the Devil himself” to cut his oat field than pay the fee demanded. The source of the harvesting is not unknown or mysterious — it is indeed Satan himself, who can be seen in the woodcut holding a scythe. According to the original text of the legend, the devil “cut them in round circles, and plac’t every straw with that exactness that it would have taken up above an Age for any Man to perform what he did that one night.” This image and story cannot be related to crop circles because it states explicitly that the crop was cut (i.e., harvested) rather than laid down, as occurs in crop circles.

Some claim that the first crop circles (though they were not called that at the time) appeared near the small town of Tully, Australia. In 1966 a farmer said he saw a flying saucer rise up from a swampy area and fly away; when he went to investigate he saw a roughly circular area of debris and apparently flattened reeds and grass, which he assumed had been made by the alien spacecraft (but which police investigators said was likely caused by a natural phenomena such as a dust devil or waterspout). Referred in the press as “flying saucer nests,” this story is more a UFO report than a crop circle report.

As in the 1678 mowing devil legend, the case for it being linked to crop circles is especially weak when we consider that the impression or formation was not made in a crop of any kind but instead in ordinary grass. A round impression in a lawn or grassy area is not necessarily mysterious (as anyone with a kiddie pool in the back yard knows). Indeed, mysterious circles have appeared in grass throughout the world that are sometimes attributed to fairies but instead caused by disease.

In fact the first real crop circles didn’t appear until the 1970s, when simple circles began appearing in the English countryside. The number and complexity of the circles increased dramatically, reaching a peak in the 1980s and 1990s when increasingly elaborate circles were produced, including those illustrating complex mathematical equations such as fractals. [Image Album: Mysterious Crop Circles Gallery]

Crop circle in Switzerland
People inspect crop circles within a golden wheat field in Switzerland. The photo was taken on July 29, 2007.
CREDIT: Jabberocky | public domain

Theories & explanations

Unlike other mysterious phenomenon such as psychic powers, ghosts, or Bigfoot, there is no doubt that crop circles are “real.” The evidence that they exist is clear and overwhelming. The real question is what creates them.

Crop circle enthusiasts have come up with many theories about what creates the patterns, ranging from the plausible to the absurd. One explanation in vogue in the early 1980s was that the mysterious circle patterns were accidentally produced by the especially vigorous sexual activity of horny hedgehogs. Some people have suggested that the circles are somehow created by incredibly localized and precise wind patterns, or by scientifically undetectable Earth energy fields and meridians called ley lines.

Many who favor an extraterrestrial explanation claim that aliens physically make the patterns themselves from spaceships; others suggest that they do it using invisible energy beams from space, saving them the trip down here. Still others believe that it is human, not extraterrestrial, thought and intelligence that is behind the patterns — not in the form of hoaxers but some sort of global psychic power that manifests itself in wheat and other crops.

While there are countless theories, the only known, proven cause of crop circles is humans. Their origin remained a mystery until September 1991, when two men confessed that they had created the patterns for decades as a prank to make people think UFOs had landed (they had been inspired by the 1966 Tully UFO report). They never claimed to have made all the circles — many were copycat pranks done by others — but their hoax launched the crop circle phenomena.

Triskelion Crop Circle
Another triskelion crop circle. The symbol can be used to represent cycles, progress or competition.
CREDIT: Thomas J. Sutter, Jr. | public domain

Most crop circle researchers admit that the vast majority of crop circles are created by hoaxers. But, they claim, there’s a remaining tiny percentage that they can’t explain. The real problem is that (despite unproven claims by a few researchers that stalks found inside “real” crop circles show unusual characteristics), there is no reliable scientific way to distinguish “real” crop circles from man-made ones. [Related: Crop-Circle Artists Becoming High Tech]

Crop circle features

While there are exceptions, virtually all crop circles share a set of common characteristics.

Circles. Crop circles, as the name implies, almost always involve circles — rarely triangles, rectangles, or squares, though some designs contain straight or curved lines.  Perhaps not coincidentally, a circle is the easiest pattern for hoaxers to create.

Nocturnal creation. Crop circles are formed overnight, often sighted by farmers or passersby the next morning. Though there seems no logical reason for extraterrestrials or earth energies to only create patterns at night, it is obviously a great advantage for hoaxers to create the designs under the cover of darkness; full moon nights are especially popular.

Camera shyness. Crop circles have never been recorded being made (except, of course, for those created by hoaxers). This is a very suspicious trait; after all, if mysterious earthly forces are at work, there’s no reason to think that they wouldn’t happen when cameras are recording. The same thing is true with other explanations including alien spacecraft; the only things ever caught on camera making the circles are hoaxers.

bird crop circle in England
This design of three flying birds was created on Aug. 3, 2003, in the county of Wiltshire in southern England. The birds, which resemble swallows, have ever-diminishing circles trailing behind their wing tips.
CREDIT: public domain

No obvious human trace. Most crop circles show little or no signs of human contact. While many people consider this very mysterious, in fact it’s quite logical: Hoaxers who devote the time and effort required to design and create the (often complex) crop circles are unlikely to carelessly leave obvious signs of their activities.

Access to roads. Crop circles usually appear in fields that provide reasonably easy public access, close to roads and highways. They rarely appear in remote, inaccessible areas. Because of this, the patterns are usually noticed within a day or two of their creation by passing motorists.

There are many theories about what creates crop circles, from aliens to mysterious vortices to wind patterns, but they all lack one important element: good evidence. Perhaps one day a mysterious, unknown source will be discovered for crop circles, but until then perhaps they are best thought of as collective public art.

Benjamin Radford is deputy editor of “Skeptical Inquirer” science magazine and author of six books including “Scientific Paranormal Investigation: How to Solve Unexplained Mysteries.” His website is