Fleas – Know the enemy, choose a weapon

Easily one of the most frustrating problems for pet owners, especially those living in tropical environments, with multiple pets on shag carpet, the flea is just a pissy little insect with a phenomenal reproductive capacity. While killing-off  the first 95% of the population is easy, getting the final few often seems near impossible..


Just as some people itch furiously from a single mozzie bite, while others are unaffected, animals vary in how allergic they are to the saliva of biting insects.  Dogs and cats allergic to fleas will itch, chew and pull out hair for up to 3 weeks after a single bite, while the non-allergic will tolerate infestation without a peep. Any dog with seasonal tail-base irritation should be suspected of flea allergy, even if you can’t see any fleas.

Flea control is more than a one-shoe-fits-all approach. What’s best for you depends upon your animals (allergies, numbers, size, lifestyle, social contact), environment (climate, recent house moves, visiting dogs, carpets, gardens, bedding, parks, and beach),  you (patience, attitude to fleas and chemicals, financial and time resources) and flea resistance.

If you’ve just got a a new furry member in the house, or your current flea control is costing heaps and/or failing, it’s time to invest some time in understanding your enemy, and selecting the weapons that best suit your situation.


Research their demographics:

  • Adults represent only 5% of the total population, live for up to 6 weeks, mostly on the animal or bedding, and produce up to 500 eggs in a lifetime. If there’s 10 fleas on your dog, there’s already 200 more in the carpet, and new eggs are being pumped out at a rate of 300 per day. Within a month the 300 eggs laid today can become adults, laying eggs of their own. The flea’s main evolutionary weapon is it’s reproductive tract. More on population growth rates here.flea triangle
  • Eggs are 50% of the population, can’t easily be killed, and are scattered all over place – in the garden, carpet, in your bed. Within a few days, they hatch into….
  • Larvae, tiny caterpillars, are 35% of the population, live for a couple of weeks, eating, avoiding light, living in bedding, carpet, sand, and in cracks. Larvae are easy to kill but, like eggs, are scattered all over the place. These build a cocoon and become…..
  • Pupae which can hatch into adult fleas within 1-2 weeks, OR can lay dormant for up to 6-9 months, waiting for good weather and a host.  For a pupa to hatch it needs at least 21C and 70% humidity, so the further north you live, the longer your flea season, the more flea trouble you’ll have.  Like Dengue fever and malaria, climate change will favour the flea.  When a pupa hatches, the infant flea must suck blood within a week, if they don’t they starve to death.


Understand their weaknesses:

If you want to get serious about flea control, especially if you wish to avoid wasting money and gratuitous use of chemicals, understanding where to attack in to the life cycle is crucial.

Adults are the most tempting target and are the focus of most pet owners, and pets. Their vulnerability is their concentration on the animal. Using insecticides (adulticides) on your pet, either on the skin or as a pill, especially long-acting ones or regularly, is like poisoning the waterhole. This approach ignores the 95% of immature forms, but if you kill enough adults for long enough, eventually the babies stop coming.

Adulticides, are the most transportable for of flea protection. If your pet is very socially promiscuous, at your place or elsewhere, and is picking up new infestations all the time, these types of agents will be an important part of your flea control program.


.Eggs are hard to kill and it’s easier to give birth control to the adults if you wanna knock off eggs.

The trouble with controlling eggs, larvae, and pupae is that they are scattered everywhere. Whether you’re using a vacuum, a chemical bomb, or borate, you’ve gotta do it all over the place, in the yard, bedding, furniture and house. This increases labour and risks of chemical overspray.

The urgency for an immature flea to feed, soon after hatching from the pupa, is a point of vulnerability. If you can work out a way of getting all your pupae to hatch when the pets are away on holidays, there’s gunna be famine out there in flea-land.


Choose your arsenal:

Weapons vary in cost and how they work. If you have a mild problem, you may only need one agent. An allergic pet in  a multi-animal household, on shag-pile, in Cairns,  may need multiple.  Combination products that also do heartworm, worming and ticks make the decision-making process more complex.

The basic priorities for selecting flea control, for most pet owners, can be boiled down to:

  • Effectiveness – the percentage of fleas killed, and how quickly
  • Ease of treatment – frequency and method – pill, spot-on, bath
  • Toxicity, to pet and human
  • Value for money

The easiest flea problems for vets to solve are those with pet owners with no concern about costs and chemical residues, who are willing to use multiple agents. The most difficult are those with multiple, flea-allergic pets, owned by those concerned about the unknown effects of chemicals on pet and man, with a small budget..

Links to each type of weapon:

  • Adulticides – Agents that kill adult fleas: baths, rinses, sprays, spot-ons, collars, and the kill pills are all covered here.
  • Breaking the cycle – lufenuron, methoprene, strategic control, starving teens, borate, vacuuming, changing the environment.


.Realistic goals:

If your dog or cat lives entirely indoors, and no other pets come into the house, it’s likely that a flea population can be completely and permanently eradicated. After using one or a combination of the weapons described above, for 6-12 months, you may be able to stop flea prevention all together, or at least until you buy that second-hand dog bed on ebay.

If your pet is not allergic to fleas, and isn’t bothered by carrying a few, or you live in a cooler climate where flea season is only 2 months a year, you may be more relaxed about flea control. Killing 80% of the population may be an adequate goal, and using just use one agent, intermittently, may be sufficient.

If you have a flea-allergic pet, live in the tropics, or worst of all, both, then you may need to use agents that kill 98+%, reliably, for long periods. Killing that final 2% may demand continuous use of 2 products, and may exceed a pet owners budget and patience..

Good rules of thumb for flea control:

  • If you see any skin problems developing over the rump or thighs in summer, look for and treat fleas early, hopefully before it’s severe enough to involve a vet. Understand that, even if you cant see fleas, they may still be the cause.
  • Treat all animals in the house, including cats. Ignoring the flea population on the pet that is not allergic, and therefore doesn’t itch, is like choosing to kill every second cockroach in your kitchen.
  • Don’t wait for the problem to get out of control, several months of unchecked breeding can land you with a few million eggs, and months of grief. Use a cheap flea comb once a week to detect the bastards early.
  • If you can’t afford to pull up the carpet, best to keep the animals off it. It’s like a giant humidi-crib specifically designed to nourish and nurture infant fleas and dust mites.

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