The flea is found in some medieval encyclopedias. It is a bothersome insect that seems to have been sent as a punishment to humans. It attacks more by night than day, biting and drawing blood, and if one tries to swat them, they suddenly disappear in flight and cannot be found. When it is thought that there are no more fleas and one will be left in peace, they quickly return to the attack, and even a furious man cannot do anything about them. An ointment made of absinthe boiled in oil and applied to the skin is all that will keep them away.