How long do cat fleas live without a host?

Adult fleas live for between one and two weeks in favourable conditions. The flea needs a host on which to feed continuously and they prefer humid and warm climates.

Fleas in a jar. Photo: PoC.

However, the flea pupae can live for up to 5 months without food or light. I think you need to understand the life cycle to know where the pupae fit into it. The mother flea is on a cat feeding on blood. She lays eggs because the blood provides the energy to do this. They are laid in clusters of 20 maximum. She can lay a maximum of 50 per day. The eggs fall off the cat as the cat walks around. They fall into, for example, carpet. 

The eggs hatch into legless embryos called larvae. They burrow deep into the carpet or the roots of plants in the wild. They live off pre-digested blood from their mother flea. They develop into cocoons or flea pupae. They can live in this state for up to 5 months without food or light.

They mature into adult fleas with a lowered metabolism so that they don't need feeding. A potential host passes by and the adult flea senses the change in thermal energy. The flea emerges from the cocoon and jumps onto their new post to feed immediately.

Fleas cannot fly but they have an enormous ability to jump. If they were the size of humans they would jump up to a thousand feet into the air. This is their mode of transport.