Class: Insects
Size: 1 to 5mm
Weight: Approx. 0.2 mg
Age: A few weeks to 1.5 years
Appearance: Six-legged, small proboscis, enlarged abdomen
Sexual dimorphism: No
Feeding type: Blood eater (haematophagous)
Food: Blood
Distribution: Worldwide approx. 2’400 species
Habitat: Near the host
Natural enemies: None
Sexual maturity: Hatched within one day
Mating season: All year round
Number of offspring: 300 to 400 eggs
Threatened with extinction: No

• More than two thousand species of fleas are known worldwide, they have colonised the earth for about 65 million years.
• They are parasites, i.e. they feed on the blood of their host. Fleas infest humans and various animal species equally.
• Fleas on dogs and cats are a nuisance that many pet owners have to deal with. The little bloodsuckers are very common. Animal fleas can also pose a health risk to humans. Because of the heavy infestation, humans are particularly affected by fleas when there are many fleas present. Various pathogens can pass to humans and cause health problems.
• Chicken fleas are temporary ectoparasites of poultry and many different wild birds. The preferred host is poultry, which can often have a permanent infestation. Pigeons, geese, ducks, pheasants and turkeys are also suitable hosts for fleas. Large numbers of chicken fleas in residential areas can become a serious health problem for humans.
• Fleas are wingless insects with six legs, the last pair of legs is very strong and somewhat elongated. This allows fleas to jump up to one metre.
• For these fast jumps, there are pads on the hind legs made of resilin, an elastic protein, which is stretched just before the jump.
• Fleas like to hide in dark corners, cracks, beds, upholstered furniture, curtains, carpets and in clothing.
• To move quickly in animal fur or on the hairy skin of their hosts, the flea has a narrow body with flat sides and is protected by an extremely hard chitin shell. For extra grip on hair, the flea legs are equipped with teeth combs and bristles. This makes it difficult to comb them out easily on dogs, for example.
• The converted mouthparts become both sucking and biting proboscis: fleas bite firmly into the skin and suck the blood while standing on their heads.
• Fleas feed on human blood, mammalian blood or bird blood, depending on the species. Some species know only one host, while others need not be choosy about survival.
• Nest fleas are very sedentary creatures that, once established, like to stay in a single nest, carpet or upholstered furniture. Fur fleas travel as stowaways in the fur of their host.
• Nest fleas like dark and dry places and only move up at night to visit their hosts.
• Flea larvae feed on organic material around the nest. After about four weeks, they grow into adult fleas. A female can lay hundreds of eggs during her lifetime.
• Human fleas, or Pulex irritans, leave groups of stinging spots on the skin that can develop into very itchy and red wheals (skin swellings) and are prone to inflammation. Therefore, when a flea bite is scratched, bacteria can enter the skin surface and cause an infection. A flea infection is a health risk that should not be underestimated; some tropical species can also transmit serious infectious diseases such as Plague or Typhoid.
• After feeding, fleas can live for up to two months without blood.