How big are flea pupae?

image of a flea pupae in its cocoon

Auguste Le Roux

Img 1 Naked flea pupae are 1.5-3.2 mm long, and 1 mm wide. With a cocoon, they’re 4-5 mm long, and 2 mm wide.


Flea pupae are 1.5 to 3.2 millimeters long, and 1 millimeter wide. However, most fleas pupate inside of cocoons. The silk structure adds to their size, making them 4-5 mm long, and 2 mm wide.


Mature Flea Larvae

Fully mature flea larvae are 4-5 mm long, and 0.5 mm wide. To prepare for pupation, they’ll fold themselves in half and begin spinning a cocoon. While doubled over, the so-called U-shaped larvae are 2.5 mm long and 1 mm wide.

Flea Pupae

While pupating, the larval head and posterior three body segments are lost. The pupal body then slightly widens and shortens. Larvae initially have a small amount of space within the cocoon. But as pupae, there’s a considerable amount of unoccupied space inside the cocoon due to the body changes. Flea pupae are near the same size as adults, 1.5 to 3.2 millimeters in length.

Flea Cocoon

Most fleas pupate within a cocoon structure, which adds to their size. The cocoon is composed of a sticky, silk-like fiber. Since it’s sticky, environmental debris adheres to the cocoon. The adhering matter increases the cocoon’s wall thickness by a millimeter. All components combined, fleas cocoons are four to five mm long, and two mm wide.


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