The flea circus is a unique form of entertainment, in which fleas act as the star performers in a miniature circus show. These tiny insects are enclosed in a glass tank, which also contains various props and accessories. Under the direction of a human ringleader, the fleas appear to perform extraordinary feats to entertain an audience. This can include walking a tightrope, kicking a ball across the tank, pulling wheeled carts, or any number of additional acts. While the popularity of the flea circus flourished through the 19th and early 20th centuries, few of these acts have survived to the present day.
Historians believe that the first flea circus took place during the 16th century, when jewelry or watch makers used performing fleas to demonstrate the delicate strength of fine necklaces or watch chains. By the 19th century, flea circuses had become a major draw in Europe, with permanent establishments in England's Leicester Square and on several of its heavily-populated streets. Throughout the 19th and early 20th centuries, entertainers continued to hold these circuses wherever fleas could be found. By the 21st century, the flea circus had become a novelty act, and the craft was taken up by magicians and circus performers. Munich's Oktoberfest is still home to a popular flea circus that has been in operation for more than two centuries.
The traditional flea circus relied on slight-of-hand tricks to create the impression that the fleas were actually performing. Realistically, fleas cannot be trained to perform, and also have a very short life. Rather than training fleas to act in these shows, entertainers would use fine gold wires to create a harness around the flea, which would remain in place for the flea's entire life. The ringmaster could then tie this harness to a ball or pushcart, which would make it look as though the flea were kicking the ball or pulling the cart across the enclosure. Fleas could even be attached to ropes or wires to make it look as though they were walking a tightrope, or being shot out of a miniature cannon.
The modern flea circus relies on a slightly different tactic to make it appear that the fleas are performing. Rather than rely on harnesses, the ringmaster incorporates electrical and mechanical actions to move a ball or pushcart. For example, a puff of air can make a ball appear to have been kicked in the air by a flea, even though the flea has done no such thing.
The 21st century flea circus may not even contain any fleas. Instead, the entertainer relies on the power of suggestion to make the audience think they see fleas in the tank. In some cases, fleas are present, but are not actually part of the act in any way. This type of show is often known as a humbug act based on the trickery on the part of the entertainer.