Fleas are small, wingless, external parasites from the order Siphonaptera. Adult fleas range from 2 to 4 mm in length, are brown in colour and oval in shape.
They have six, spiny legs, with powerful hind legs for jumping. Fleas are able to jump more than 200 times their body length.
Fleas have small antennae and mouth parts for piercing and sucking. They feed on the blood of humans and animals. Some flea species feed from one host species only, while others can survive on a number of hosts.
Fleas may be a growing problem due to the increasing number of household pets.
Fleas can spread the typhus disease. Typhus is caused when flea bites become infected as a result of flea-faecal contamination. However, this is uncommon.
Fleas are also known to transmit tapeworm larvae. Fleas are most notorious for transmitting bubonic plague from wild rodents to humans in some parts of the world. However, this is not known to occur in Australia.
Main flea species in Australia are:
- Cat flea, which is the most common flea in Australia. It attacks dogs, rats, humans and other mammals.
- Dog flea, which is less common than the cat flea, but similar in appearance. This flea attacks a wide variety of mammals.
- Human flea, which is uncommon due to the increase in home hygiene standards. This flea also attacks dogs, pigs, rats and mice.
Fleas – life cycle
Fleas take four forms during their life cycle: egg, larva, pupae and adult. This cycle takes 2 weeks to 8 months depending on temperature, humidity, food and the type of flea species.
You may need to identify which stage of the flea life cycle is present before deciding on a treatment method.
Adult females lay 4-8 eggs in a cluster after a blood feeding, usually on the host animal. The eggs are light coloured and oval shaped, and can take 2 days to 2 weeks to hatch.
Larvae look like translucent worms with small bristles. They are approximately 3 mm long. Larvae may take several months to develop after hatching from eggs. They eat digested blood from adult flea faeces, dead skin, feathers, hair and other particles of organic matter. Once fully developed, larvae begin weaving a cocoon and become pupae.
Pupae grow to adult fleas inside a cocoon that sticks to pet hair, carpet fiber, dust, grass cuttings and other matter. Fleas grow best during warm, moist winters and spring. Pupae do not emerge from these cocoons until they detect a suitable host (for example, by sensing vibrations caused by humans or animals). Egg to pupa stages take approximately 5-14 days.
Adult fleas may remain resting in their cocoon until they sense vibration (caused by movement), pressure, heat, noise or carbon dioxide. The ability to sense vibration explains why flea bites can occur after entering a house that has been unoccupied for some time.
When adult fleas emerge from their cocoons, they are ready for their first blood feed. Adults are quite active, crawling and jumping in hair or fur.
Adult fleas can survive for many months without feeding. When a food source is available, the flea uses its saw-like mandibles (jaws) to cut through skin on accessible parts of the body (for example, legs or feet). Flea saliva contains anticoagulants to keep the host’s blood flowing so they can feed easily.
Symptoms of flea bites include:
- extreme itchiness at the bite site
- a red, swollen wheal (lump) that develops within 30 minutes of being bitten
- a blister or small wound at the site of the wheal, approximately one day after being bitten
- bites concentrated on the legs and feet
- secondary infections caused by scratching the bite site
Some people may become more sensitive to flea bites over time.
Flea reservoirs – household pets
Dogs and cats are common ‘reservoirs’ for fleas.
Pets may be irritated by flea bites and scratch often. Check for fleas by parting the fur, particularly around the ears and rump. Look for the fleas themselves or for flea faeces. Flea faeces look like miniscule dark specks. For a positive identification, place a few of the specks on a piece of lightly moistened white tissue. Flea faeces will stain the tissue with a ring of blood.
Fleas – nonchemical treatment
Maintaining a high standard of hygiene is very important in controlling fleas without the use of pesticides. All hard floors and furnishings should be thoroughly swept and washed. All carpet and furnishings should be vacuumed, paying particular attention along seams and joins.
Soft furnishings and beddings should be washed.
It is common for fleas to be found in areas where household pets rest. These areas should be targeted first. Pet bedding should be thoroughly vacuumed or steam cleaned.
Outside, loose debris and weeds should be removed and the lawns mowed. This helps expose their environment and is a good integrated pest management tool. Larvae have been known to frequent shaded areas.
Ensuring pets and animals cannot access areas beneath the house can also help to minimise the chance of fleas spreading indoors.
Fleas – chemical treatment
Effective flea control often relies on the well-directed application of pesticides. This should be undertaken at the same time as non-chemical treatment – such as vacuuming and garden maintenance – to ensure the environment is less suitable for the development of fleas.
1. Treat the pet
Pest control operators (PCOs) should direct their clients to treat pets for fleas. This will ensure that the fleas do not continue to reinfest treated areas while harbouring on the animal. Clients should contact a local veterinary clinic for advice on appropriate pet flea control measures. Care must be taken to ensure untreated stray or feral animals do not also inhabit the property. Pets bedding should be treated simultaneously.
2. Treat the home
There are many types of pesticides registered for flea control in Australia. When selecting a pesticide, the PCO should perform a risk assessment. Before starting a treatment, the PCO should consider whether they have:
- chosen a pesticide with the lowest toxicity
- enquired if any members of the household are sensitive to pesticides
- communicated to the client areas where pesticides will be applied
- informed the client to vacate the premise for a minimum of 4–6 hours
- ensured all children’s toys, and pet water and food bowls are stored away
- read the product label directions carefully.
Surface sprays can be used to treat areas that may harbour eggs, larvae, pupae or adults. Typically, these areas may include flooring, skirting boards under rugs, and floor to wall joints. Particular care must be taken in the accuracy of the application, especially when using products that are not suitable for carpets and upholstery.
Space spraying with pesticides can be a useful control method. The PCO must prevent entry to treated areas during the time of application. Treated rooms should be adequately ventilated before persons and pets are allowed to re-enter.
Dusting – while not common – can be an effective application method when treating areas where spraying is difficult, such as in cracks and crevices, or wall voids. Take care when using dusts. They do not adhere to the surface on which they are applied and can be disturbed by air flow or vibrations, potentially increasing the treatment area and prolonging the risk of exposure.
3. Treat the garden
Sometimes outdoor areas and subfloors may need to be treated with surface sprays. Sheds and dog houses may also need to be treated. Rodents can sometimes be the source of a flea infestation.
Therefore, PCOs should look for signs of rodent activity when deciding what chemical treatment to recommend. Rodent and flea control measures may have to be undertaken simultaneously.