The longevity of laboratory-reared fleas, two species parasitic on domestic rats and six species parasitic on wild rodents of the sylvatic plague reservoir, was studied. The 10,795 adult fleas used in these studies were maintained at different temperatures and humidities within a range encountered in their natural habitats. Different conditions of host availability were simulated by feeding some adult fleas only once, at the beginning of an experiment, by feeding others daily, and by not feeding others at all.

Generally, a single blood meal exerted a beneficial effect on the fleas in that those fed before starvation survived a little longer than those that were never fed.

With the exception of Opisodasys nesiotus, all fleas were potentially long-lived under some of the laboratory conditions. The longest-lived fleas in all instances were those kept at high humidities (90% relative humidity or more) and fed daily. An O. nesiotus male survived for 48 days, the longest period of any of this species. The maximum longevity for each of the other species was among females and was as follows: Xenopsylla cheopis, over 5 months; Malaraeus telchinum, over 6 months; Nosopsyllus fasciatus, over 9 months; Orchopeas sexdentatus sexdentatus, 10½ months; Diamanus montanus, over 11 months; Oropsylla idahoensis, nearly 12 months; Megahothris abantis, nearly 16 months.