BugWise

What do fleas look like?

A cat flea. Electron micrograph: S Lindsay © Australian Museum.

Flea. Illustration: A Howells © Australian Museum.

Size:

0.5 mm - 10 mm in length but most are shorter than 5 mm.

Body:

Very thin as if pressed from the sides.

Covered with hairs and spines directed backwards, some in comb-like formations.

Appears hard.

Antennae:

Very short, held in a groove hence often difficult to see.

Never longer than body.

Eyes:

Very small or absent.

Mouthparts:

For piercing and sucking.

Wings:

Absent.

Limbs:

Six legs.

Hindlegs enlarged and modified for jumping;

Have claws modified for clinging to feathers and hair.

Abdomen tip:

Cerci (tails) absent.

Where are fleas found?

• On mammals and birds (rarely) among hairs or feathers.
• Few are found on semi-aquatic animals such as the platypus, but never on marine mammals.

What do fleas do?

• Fleas are external parasites. They maybe found alone or in large numbers on suitable hosts.
• When disturbed they jump. They can jump incredible distances.
• They feed on blood.
• They are active during the day.

What looks similar?

• Flies that do not have wings can be mistaken for fleas. Unlike fleas, wingless flies are never thin as if pressed from the sides.
• Lice differ from fleas in that they are flattened as pressed from above, do not jump when disturbed, and can occur on fully aquatic hosts.