Author: Juli Chamberlin
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Fleas and Your Pet
Fleas are not only an itchy nuisance, but may also be a disease risk for you and your pets. Cats and dogs can develop mild to severe flea allergy dermatitis, flea bite anemia, and internal parasites like tapeworms. People, especially children, are sometimes exposed to the parasites through interaction with flea-infested pets.
A pet’s first introduction to a flea is usually outdoors – indoor pets rarely host fleas. In northern and Midwest states, fleas are seasonally active during spring, summer, or both. In southern and tropical states, they are active most of the year. Fleas favor warm and moist conditions, from 70 to 90° F and above 75% humidity.
Other sources of fleas include used rugs and upholstered furniture, as well as visiting animals. Adult fleas jump onto a new host either from an infested animal or from the areas where an infested animal rests. In a yard, moist and shaded soil in warm weather is attractive both to fleas and their hosts. Once on a pet, an adult flea burrows to the skin, bites the animal to get a good blood meal, and then settles in to reproduce.
Understanding The Flea Life Cycle
Understanding the flea life cycle is essential for effective flea control solutions. The most obvious symptoms of a flea infestation are pets scratching repeatedly, grooming themselves excessively, or biting their skin. On closer inspection, you’ll be able to see small black adult fleas crawling in your pet’s fur.
An adult female won’t lay eggs until she’s had a blood meal, but it only takes one meal for the female to start laying 25-50 eggs per day. The tiny, white flea eggs are slippery and usually fall out of the pet’s fur. You’ll notice what looks like salt (the eggs) and pepper (adult flea feces) in places where your pet sleeps. The eggs hatch into larvae in two days to a few weeks, depending on temperature and humidity.
Flea eggs (white) and flea feces (black) will be noticeable in areas where your pet sleeps.
The white, worm-like flea larvae feed on dried blood, adult flea droppings, and pet fecal debris that tend to shed into sleeping and grooming areas. Flea droppings – or ‘flea dirt’ – is easier to see than either larvae or eggs and turns reddish brown when moistened. In as few as five days, but up to a month, a larva will spin a cocoon to pupate, being transformed within the cocoon to an adult flea.
The pupal stage can last as few as five days or up to a year. Floor vibration from an approaching pet or person can trigger the immediate emergence of an adult from its cocoon, ready to jump onto a pet or person. This is the primary way that people get bitten. Multiple red and itchy bites, especially in a row, can be the work of a single hungry flea.
Adult fleas represent just 5% of the fleas present in an infested home, whereas eggs represent 50%. In order to successfully control fleas, it is important to remove fleas in all stages from your pet and your home. Because the flea life cycle is 18 to 28 days under prime conditions, it is important to make sure your control efforts are implemented throughout the entire life cycle.
Low Impact Approaches
The following flea control measures are effective when implemented in combination to kill adult fleas, eggs, larvae, and pupae. Monitor the success of your flea control plan by checking pet sleeping areas regularly for any sign of fleas.
Indoors
Vacuuming is highly effective at removing fleas in any life stage from their favorite haunts: carpets, cushioned furniture, floor cracks and crevices, and pet play structures. Because vacuuming collects fleas but does not kill them, put some tape over the end of the vacuum cleaner hose to prevent fleas escaping from the bag, or transfer the bag to an outdoor waste bin or .
Laundering
Hot, soapy water acts as an effective means to kill fleas in all life stages with no health risk to pets or people. Wash pet bedding weekly to treat an infestation. Place towels in pet resting areas to make laundering easier. Whenever you are handling pet bedding that may contain flea eggs, fold it up carefully so the eggs do not fall out of the bedding and land on the floor or furniture.
On your pet
Flea combs are made to remove adult fleas, flea dirt, and dried blood from your pet’s skin and fur. They are highly effective and pets often enjoy the process. Focus on head and neck, but groom your whole pet if possible. Pull the fleas out of the comb and drop them into soapy water before they have a chance to jump away. During active flea infestations, grooming twice daily may be needed; otherwise, several times per week just to check for fleas.
Bathing
A thorough bath using regular pet shampoo and hot water kills adult fleas as effectively as flea shampoos and dips that contain pesticides, and is safer for you and your pet. Before you fill the tub, start by putting a ring of concentrated soap around your pet’s neck so they can’t escape from the bath water by crawling onto the pet’s head. Cats prefer grooming to baths, but for dogs or long-haired cats, bathing is a superior control technique.
Outdoors
Flea habitat reduction
Fleas live only in warm, moist areas that are protected from direct sunlight and heavy rain or irrigation, and have frequent visits from host animals. Even if you have an infested pet and home, you may not have an outdoor flea problem. Wearing knee-high white socks, check for fleas in likely places – if fleas present, they will jump onto your legs. You can then expose these spots to sun through mowing or pruning, or simply flood the area periodically.
Clean outdoor pet shelters by laundering any bedding and vacuuming inside thoroughly. Seal off any outdoor hiding places where pets or other furry animals may sleep. Manage pet resting spots to prevent fleas from establishing a population in your yard.
Biological control
Some studies have shown that several species of nematodes can control fleas outdoors by becoming parasites on flea larvae without affecting plants, pets, or people. Studies indicate that use of these beneficial nematodes, available at garden supply stores, works best in sandy soil that has been watered before and after the nematodes are added.
Flea Control Pesticides
Review all your options before deciding on a treatment plan. If you decide to use flea control chemicals, the GreenPaws Flea and Tick Product Directory provides guidance for selecting the lowest-toxicity products and avoiding high-toxicity products to prevent poisoning pets, family members, and yourself. If you choose to choose to work with a pest control professional, be sure the company is Ecowise or GreenShield certified and familiar with Integrated Pest Management techniques.
Potential Consequences of Flea Control Pesticides
Recognize that when you use flea control pesticides, you should be ready to deal with these potential consequences:
- Accidental poisoning from use of foggers or flea bombs.
- Exposure to pesticide residues that remain in the home environment from use of flea control products.
- Exposure to potentially hazardous chemicals from residue on pet fur.
- Accidental pet poisoning due to misuse of pesticide products, especially on smaller dogs and cats.
- Risk of poisoning from residue on pet fur for multiple cats or dog households with spot-on treatments, since animals may groom each other.
Precautions to Take When Using Flea Control Pesticides
If you determine that pesticides are necessary, take these precautionary steps to reduce the potential for adverse effects:
- Always read and follow the label instructions on the pesticide product. The label is the law and you could be liable for any damage resulting from not following the label instructions.
- Use only US EPA and FDA approved products, and review labels for products you have used in the past. Some flea control products cannot be safely used on cats, and correct dosing always depends on both age and weight. EPA is in the process of revising product label and packaging requirements in light of increased adverse effects on pets from spot-on products (see Regulatory Update below for details).
- For prescription flea treatment options, consult your veterinarian.
- Once you have an infestation under control, evaluate the need for continued pesticide and prescription product use. For indoor pets, there is typically no need to treat regularly for fleas.
Types of Flea Control Pesticides
Flea control products are formulated to kill fleas at various points in the flea life cycle and are available for the full range of on-pet, indoor, and outdoor use. Flea product formulations include spot-on treatments, powders, aerosols, collars, shampoos, soaps, and dips. When using these products, minimize your exposure to pesticides by observing these precautions:
- Spot-on treatments: Avoid touching fur around the treated area.
- Powders: Avoid breathing dust and wear a dust mask.
- Aerosols (sprays, foggers): Avoid these type of products altogether due to high risk of inhalation during release of the spray aerosol.
- Collars: Avoid touching collars or area near collar.
- Shampoos, soaps, and dip: Wear rubber gloves for protection.
Due to the wide range of available flea products and allowed use, it is important to be informed about the ingredients contained in a flea control product and to understand the risks associated with those ingredients. Below are comparison tables that highlight different types of flea control products.
Diatomaceous Earth
Diatomaceous earth is a silica-based dust that dries out and abrades flea eggs and flea larvae. It should be applied to carpets, along baseboards, and on cat scratching posts. Leave it down for a few days to a week and then vacuum it up. It is not toxic if it is eaten by accident, but it is not good to breathe the dust, as it is highly irritating to the lungs. Keep children and pets away and wear a dust mask when applying the product.
Prescription Veterinary Drugs
If you decide to use prescription drugs to control fleas on your pet, discuss your treatment options with your veterinarian. Prescription flea control drugs are available as topical (spot-on) treatments, oral (pill-form) treatments, and injections. Topical treatments present a risk of exposure from residue on pet fur to children and pets.
Also keep in mind that while your vet might be a good resource for deciding on a prescription treatment for your pet, your vet may not be a good point of reference for implementing flea control options that include Integrated Pest Management (IPM), since most veterinarians are not trained in IPM techniques.
Aerosol Sprays
Use of aerosol sprays, foggers or flea bombs is not recommended, due to the high probability of harm during the application from inhaling the aerosol. Fogging also leaves pesticide residues that remain distributed throughout the home environment. In addition, these products are unlikely to kill all the fleas in your home due to fact that larvae burrow into carpets where they can survive these applications.
Outdoor sprays can drift away and pose a risk to non-target wildlife such as bees or other beneficial insects. In addition, insecticides used in outdoor flea control products have become less effective due to widespread flea resistance.
Lower-Impact Pesticide Flea Treatments
| Chemical Classes & Active Ingredients | Hazards | Product Formulations | On-Pet | Indoor Premises | Outdoor Premises |
|---|---|---|---|---|---|
| Insect growth regulators (off-the-shelf): S-Methoprene, pyriproxifen | Low acute toxicity for pets and people, and not likely to cause cancer or other long-term harm. S-Methoprene is not suitable for outdoor use because it breaks down quickly in sunlight and shows some toxicity to aquatic wildlife. Look for products containing only an insect growth regulator as the active ingredient. Avoid products that also contain a higher toxicity insecticide such as permethrin or fipronil. | Collar, Dip, Spot-on treatment, Pet shampoo, Spray, Wipe-on | x | x | x |
| Insect growth regulators (prescription): Lufenuron* | Low toxicity to people. Some dogs and cats have shown toxicity symptoms including itchiness, vomiting, lethargy, diarrhea, and loss of appetite. | Injection, Food additive, Pill | x | ||
| Nitenpyram* (prescription) | Low toxicity to people. There are no veterinary reports that indicate toxicity to pets. Long-term studies have not been conducted. | Pill | x | ||
| Selemectin* | Initial data indicates very low toxicity to people and pets, but further safety evaluation is warranted given that residues on pet fur have been detected. | Spot-on treatment | x | ||
| Ethofenprox (also called etofenprox) | Unlike standard pyrethroids (see Table 1 above), ether pyrethroids are registered for use on cats and are somewhat lower in toxicity to pets and people. EPA classifies ethofenprox as a likely carcinogen at high doses, but unlikely at low doses. | Spot-on treatment | x | ||
| Spinosad | Not for use in cats. Low acute toxicity for dogs and people, and not likely to cause cancer or other long-term harm. Long-term studies have not been conducted. | Pill | x | ||
| Mineral compounds: Diatomaceous earth (silicon dioxide), boric acid | Low toxicity to pets and people, especially when use is confined to out-of-reach areas. Avoid inhalation and skin exposure during and after application. Boric acid has shown some evidence for reproductive toxicity and diatomaceous earth is listed by the State of California as a known carcinogen for occupational exposure (not listed by EPA). | Dust | x | x | |
| * Products containing this chemical are FDA-approved veterinary drugs rather than EPA-registered pesticides and may require a prescription. | |||||
Pesticide Flea Treatments to Avoid
| Chemical Classes & Active Ingredients | Hazards | Product Formulations | On-Pet | Indoor Premises | Outdoor Premises |
|---|---|---|---|---|---|
| Amitraz | Classified by the EPA as a Possible carcinogen. Listed by the State of California as a known developmental toxicant. Some evidence for endocrine disruption. | Collar, Spot-on treatment | x | ||
| Carbamates: Propoxur, Fenoxycarb, Carbaryl |
All 3 chemicals are toxic to the nervous system of pets, people, and bees. Acute poisoning cases have been reported with pets and people. Some carbamates show developmental and reproductive toxicity as well. All 3 chemicals are classified by EPA as a likely carcinogens and 2 are also listed by the State of California as known carcinogens. Pets and children face particular risk due to exposure to residues on pet fur, especially from collars containing propoxur. | Collar, Dip, Dust, Spray | x | x | x |
| Dinotefuran | Toxicity data is lacking for pets and people. Further safety evaluation is warranted. | Spot-on treatment | x | ||
| Essential oils: Pennyroyal (also known as fleabane), D-limonene, linalool, citrus oils, tea tree, lavender, clove, eugenol, cinnamon, eucalyptus, rue, bay, geranium. |
Many are highly toxic to pets, especially cats, through skin or oral exposure. In people, they can cause skin irritation, allergic reaction, asthma, and sun sensitivity. Pennyroyal is toxic to people if ingested. D-limnonene, derived from citrus, is used in pet-repellant products, making it unsuitable for use on pets and pet bedding to control fleas since pets do not like the scent. | Spot-on treatment, Shampoo, Spray | x | x | |
| Fipronil | Toxic to the nervous systems of pets and people. Classified by EPA is a possible carcinogen. Studies indicate that residues are present on pet fur, presenting particular risk to children and pets. Breaks down into a much more potent toxic compound in sunlight, making it hazardous for use on pets who spend significant time outdoors. | Spot-on treatment, Spray | x | ||
| Imidacloprid | May be toxic to the nervous systems of pets and people, though insects are more susceptible. Highly toxic to bees. | Spot-on treatment | x | ||
| Metaflumizone | While little data about toxicity exists, lab animal studies have shown toxicity to the nervous system and liver at high doses. Because it can leave a residue on pet fur and is absorbed through the skin, further safety evaluations are needed. | Spot-on treatment | x | ||
| Organophosphates: Malathion |
Toxic to the nervous systems of pets, people, and bees. Classified by EPA as a possible carcinogen. No longer available for indoor use. | Dust, Spray | x | ||
| Organophosphates: Tetrachlorvinphos (TCVP) |
Toxic to the nervous systems of pets and people. Acute poisoning cases have been reported. Classified by the EPA as a Likely carcinogen. Some evidence for endocrine disruption. Pets and children face particular risk due to exposure to residues on pet fur, especially from collars. | Collar, Powder, Spray | x | x | x |
| Pyrethrins | Highly toxic to cats. Unlike synthetic pyrethroids, these naturally derived compounds break down quickly and have low risk for long-term toxicity. However, they are toxic to the nervous systems of people and pets, and can trigger allergic reactions and asthma. Classified by EPA as a Possible carcinogen. | Dip, Pet Shampoo, Powder, Spray | x | x | x |
| Pyrethroids: Permethrin, bifenthrin, bioallethrin, cypermethrin, cyfluthrin, cyhalothrin, deltamethrin, esfenvalerate, tetramethrin, |
Highly toxic to cats, and toxic to the nervous systems of pets and people. Many of these compounds, including permethrin, are classified by the EPA as Likely or Possible carcinogens. People can become sensitized to pyrethroids, triggering asthma or allergic reactions. Some evidence for endocrine disruption. Pyrethroids are highly toxic to bees. Flea resistance is also an issue for effectiveness. | Dip, Spot-on treatment, Dust, Pet Shampoo, Spray | x | x | x |
Regulatory Updates on Flea Control Products
Between 2007 and 2008, US EPA noted a substantial increase of reported harm to pets from the use of spot-on flea and tick control products. In 2009, the agency issued an advisory on approximately 70 flea control products and began a process of intensive review. In many of the reported poisoning incidents, pets experienced effects such as skin irritation, skin burns, or seizures. In a few cases, pets died. The EPA’s analysis revealed special areas of concern for puppies, small-breed dogs, and cats. The biggest concern for cats was found to be harm from the use of the more concentrated products intended for dogs.
In 2010, EPA announced a plan to increase the safety of spot-on pesticide products for flea and tick control by making changes to product labels and developing more protective testing and evaluation requirements for both new and existing products. Some products may be removed from the market altogether. As of April 2013, EPA is still in the process of making these changes.
References and Additional Resources
- PRI Pesticide Product Evaluator: Find out about the hazards of specific pesticide products.
- University of California, Davis IPM Online: Pests of homes, structures, people and pets.
- Purdue University, Department of Entomology: Information on disease hazards posed by cat fleas and other types of fleas
- National Pesticide Information Center: Provides objective, science-based information about flea control pesticides and other control methods to facilitate informed decisions.
- US Environmental Protection Agency:
