Fleas are very small, dark-colored insects. They are capable of jumping long distances relative to their size; this behavior makes them easy to distinguish from specks of dirt, nymphal ticks, and other similar-size insects that don’t jump.

On your pet, you may notice scratching or other skin irritation, live fleas, or flea droppings, which look like small black granules.


Ticks are capable of transmitting disease to  humans and pets, including rickettsiosis, typhus, and plague. These diseases aren’t common in San Mateo County, but contact with fleas should be avoided. Flea bites can also cause allergic reactions and skin irritation in both people and pets.


Flea infestations can occur even in homes without pets; this most commonly occurs when wild or feral animals are making their dens under the home. These issues must be addressed at the same time as other flea control measures to avoid repeated infestations.

To prevent flea infestation, you should treat your pet(s) with an appropriate flea preventative; ask your veterinarian what products are recommended for your pet. Many products designed for dogs cannot be used on cats. Both oral and topical products are available.

If your home is already infested with fleas, you will need to vacuum carpets, rugs, cushions, upholstered furnishing, and all crevices in the home. Wash your pet’s bedding, too. Focus on areas where you have been bitten by fleas or where your pet spends most of his time. You may have to do this regularly for some days or weeks to eliminate the infestation.

You may need to use an insecticide on infested carpets and furniture; as with any pesticide, you MUST read and follow the label to avoid harm to people, pets, or the environment. Make sure the product you choose is labeled for indoor flea infestations, and that you apply it only as directed. In most cases, you will not need to use an insecticide for fleas outdoors.

Need More Help?

While the District doesn’t do residential or commercial pest control, we’re happy to help by identifying suspected flea specimens, conducting an inspection for wildlife or rodent problems that may be contributing to your problem, and providing advice for flea control in and around your home.

General information on fleas and flea control is available from the UC IPM program webpage. More information about flea control for pets is available from the American Veterinary Medical Association webpage.