Adult fleas are about an eighth of an inch long. They're reddish-brown and very thin. It's hard to really see what they look like without a microscope (though it's easier on a light-colored fur), but they do have big back legs.

Are fleas brown or black?

Fleas are small, wingless, flat insects with three pairs of legs. Adult fleas are about 1/8 of an inch long (1 to 3 mm). They are dark reddish-brown in color and have biting mouthparts. They can be very hard to spot because they move so fast along the animal's body.

What Colour are human fleas?

Human fleas and Oriental rat fleas are colored reddish-brown. Flea larvae are whitish and do not have eyes or legs.