The most common species of flea encountered within homes in which a pet lives is the cat flea, Ctenocephalis felix. Cat fleas can bite any species of mammal given the opportunity, including humans, cats and dogs. Flea bites may become swollen and inflamed, and often lead to secondary infections due to excessive scratching. Pets may develop allergic reactions to flea bites, in which case symptoms are likely to be much worse.
Flea life cycle
The life cycle of a flea involves four main stages: the egg, the larva, the pupa and the adult. Fleas are spread from animal to animal mostly in the adult stages of the life cycle. An adult flea can jump up to 100 times its body length, and this is the method by which fleas usually spread to new individuals. Once a flea lands on a pet, it will feed on the blood using its piercing and sucking mouthparts. Only the adult flea feeds on animal blood.
Adult female fleas lay eggs on the coat of the host animal, but these eggs easily drop off and may end up on pet bedding or carpets and soft furnishings around the home. A single female can lay up to 500 eggs in a lifetime, but usually lays smaller batches of around 20 eggs. The time taken for the eggs to hatch depends on temperature and humidity, varying between 2 and 16 days.
The flea larvae are active and able to move away from light. They live on house dust and the droppings of adult fleas, so this life cycle stage usually lives away from the animal host. Larvae grow for 7 to 10 days before spinning a cocoon in which the adult flea develops. The pupal stage usually lasts between 10 and 17 days, but the flea can remain dormant inside the pupa for several months if the temperature is low enough. Once the adult flea emerges, it will immediately seek a blood meal from an animal host.
Using insecticides to kill fleas
In order to control fleas, it is necessary to disrupt their life cycle and prevent them from breeding over a period of time sufficient to eradicate the population of parasites within the household. Most insecticides available are only effective on certain life-cycle stages, so this should be considered when formulating an appropriate control plan.
A number of insecticide preparations are available from veterinary surgeons to kill adult fleas. Consult your vet for the best product to suit your needs. Examples include Fipronil, which kills adult fleas within 24 hours and also has a residual effect lasting for several weeks. Imadacloprid kills adult fleas for up to four weeks and also has some effect on other life cycle stages. Lufenuron can be administered as an injection or orally, but does not kill fleas. It works by preventing eggs from hatching, thus disrupting the life cycle of the parasite. Nitenpyram is a tablet which kills adult fleas within minutes of administering but has no lasting effects. Vets will sometimes advocate using more than one of these insecticides in combination for improved control.
Shampoos and other flea-control products are available from supermarkets and other stores, but products sold over the counter are only allowed to contain a small amount of the active ingredient, so are generally less effective. It is important to select a product appropriate for your pet: some dog formulations can be dangerous for cats.
Other control measures for dealing with fleas
Thorough vacuuming is necessary to remove all life cycle stages when attempting to control a flea infestation. This is particularly true since many insecticides are not effective on the eggs or larval stages. Cracks and crevices in floors and walls must be vacuumed, together with all floors and soft furnishings, particularly those areas where pets are allowed to roam. Hard floors should also be swept and washed, and pet toys must also be thoroughly cleaned.
Sources
“Fleas” The Bohart Museum of Entomology
“Fleas” Glasgow City Council (2007)
“ Flea Control ” Summer Hill Veterinary Centre”
Veronica Mitchell - Veronica studied veterinary medicine at Cambridge University before becoming a secondary school science teacher. She enjoys writing about ...
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