Fleas are external parasites, living off the blood of mammals and birds. The most well-known are those fleas found on cats and dogs (Cat flea - Ctenocephalides felis) but other species are also common.
Some flea species include:
- Cat flea (Ctenocephalides felis)
- Dog flea (Ctenocephalides canis)
- Northern rat flea (Nosopsyllus fasciatus)
- Oriental rat flea (Xenopsylla cheopis).
In most cases, fleas are just a nuisance to their hosts, but some people and some animals suffer allergic reactions to flea saliva resulting in rashes. Flea bites generally result in the formation of a slightly-raised swollen itching spot with a single puncture point at the centre.
Fleas can carry and transmit disease. One example of this was the transmission of bubonic plague from rodents to humans. However, in Australia the most common disease transmitted from rats to humans is Murine typhus (endemic typhus) fever. In some cases dog and cat tapeworm can also be transmitted by fleas.
Fleas pass through a complete life cycle consisting of egg, larva, pupa and adult. Completion of the life cycle from egg to adult varies from two weeks to eight months depending on the temperature, humidity, food, and species. Normally after a blood meal, the female flea lays about 15 to 20 eggs per day - up to 600 in its lifetime - usually on the host (dogs, cats, rats, rabbits, mice, squirrels,possums, foxes, chickens, humans, etc.). Eggs loosely laid in the hair coat drop out almost anywhere, especially where the host rests, sleeps or nests (rugs, carpets, upholstered furniture, cat or dog boxes, kennels, sand boxes, etc.).
Eggs hatch between two days to two weeks into larvae which can be found indoors, in and along floor cracks, crevices, along baseboards, under rug edges and in furniture or beds. Outdoor development occurs in sandy gravel soils (moist sand boxes, dirt crawlspace under the house, under shrubs, etc.) where the host may rest or sleep.
Larvae take a week to several months to develop. Their food consists of digested blood from adult flea faeces, dead skin, hair, feathers, and other organic debris; larvae do not suck blood. Pupae mature to adulthood within a silken cocoon woven by the larva. In about five to fourteen days, adult fleas emerge or may remain resting in the cocoon until the detection of vibration (pet and people movement), pressure (host animal lying down on them), heat, noise, or carbon dioxide (meaning a potential blood source is near). Most fleas hibernate in the larval or pupae stage with survival and growth best during warm, moist winters and spring. "Flea season" is traditionally at the end of summer and in early autumn, but in warmer areas can last year round.