Fleas removed from their host will die of starvation within four days. Young fleas that haven’t fed can live slightly longer without a blood meal, around one week. Pre-emerged adults, remaining inside their cocoons, can enter into a dormant-like state. They can survive for up to 155 days without feeding.
Adults within Cocoons
After pupating, adult fleas can remain quiescent (dormant-like) within their cocoons for an extended period of time. Their metabolic activity is slowed down, allowing them to survive without food. Depending on ambient temperature, cocoon emergence can be delayed as long as five months. However, the quiescence quickly ends once a nearby host is detected.
Emerged, Unfed Adults
After emerging from their cocoons, adult cat fleas must quickly find a host. Without blood, they’ll die of starvation within a week in normal household conditions Fig 1.
Fig 1 Days it takes (y-axis) for 90% of newly-emerged, unfed adult fleas to die at various relative humidity percentages (x-axis).
Unfed adults can live slightly longer in more favorable, humid environments. They’re capable of surviving as long as 15 days at 75.2°F (24°C) and 78% relative humidity (RH). And at 72.5°F (22.5°C) and 60% RH, they can live for 12.3 days.
The best conditions for survival occur in cool, very humid environments. Some unfed fleas have been observed to live for up to 40 days. In one experiment, 62% of emerged adults survived up to 70 days in cool, saturated air. These conditions rarely occur within homes or natural environments.
Fleas Removed from their Host
Fleas quickly begin feeding once a host is acquired, often in less than a minute. After 24 hours of feeding, a previously unfed flea will nearly double in weight and triple in soluble protein content. When removed from the host and starved for 12 hours, all of the gained weight and most of the protein is lost. Thus, fleas must feed at least every 12 hours in order to stay well-nourished.
Blood Dependency & Starvation
Fleas typically die of starvation within four days of being removed from their host. When a young flea acquires a host and begins feeding, it’ll cross a threshold of dependency within a few days. Once this point is reached, the flea requires a constant source of blood for survival.
One study observed previously unfed fleas. When the fleas fed from a host for five days, and were then removed, death occurred within 2-4 days. When the feeding time was restricted to 12 hours, the fleas didn’t reach the point of dependency, and some lived as long as 14 days after being removed from the host.
Females Starve Sooner than Males
Fleas are anautogenous, which means they require host blood to successfully mate and reproduce. And females need a blood meal before every egg deposition. As a result, actively reproducing females must feed continually in order to keep their metabolism in balance for egg production. These females may die in as little as 24 hours after host removal.