Flea - natural history

• there are approximately 2,000 species of flea
• most relevant to humans are the cat flea (Ctenocephalides felis felis) and the dog flea (Ctenocephalides canis) - the cat flea has low host specificity and, in the UK, is the most common flea on cats and dogs
• rabbits are increasingly being kept as 'house rabbits' are also harbour fleas
• flea life cycle
  • fleas develop into adult fleas via larval, pupal and pre-emerged adult states
  • cycle takes from 2 weeks to 6 months
  • an adult cat female flea will lay about 25 eggs per day when it is about 1 week old - the hatching of eggs is influenced by humidity and temperature
  • larvae - feed on adult flea faeces and are 2-5mm long; in households often develop in carpets and burrow away from the light. The larvae is relatively fragile and will not survive dessication or high temperatures
  • pupal stage - quite resistant
  • pre-emerged adult stage - quite resistant. The main stimuli for the pre-emerged adult flea to emerge from the cocoon are pressure, vibration (e.g. someone walking across a carpet) and warmth
  • adult stage - may survive for weeks without feeding if conditions are favourable and then will feed within seconds of landing on a host. A cat flea may jump up to 34 cm to feed on a host. When a flea takes a blood meal then saliva from the flea is deposited into the skin. The saliva contains anticoagulant chemicals and is why a flea bite may display a central haemorrhagic spot
• about 95% of the population of fleas related to a pet will be in the form of eggs, larvae and pupae (i.e. in the household) and not on the animal
• pre-adult fleas may survive for more than a year after the death of a pet

Reference:

1. Dermatology in Practice (2003), 11 (5), 22-26.