“Ouch! What bit me?”

“Why is the dog so itchy?”

“Ahh! They’re all over the house!”

All of these are phrases you may hear in a home infested with fleas. Fleas are an often-overlooked aspect of pet ownership, as our dogs and cats represent the most common way that fleas find their way into our homes. This typically occurs when a wild animal carrying fleas, or a stray animal, finds its way into your yard. They drop off some of their hitchhikers, who then happily find their way to you or your pet, and then enter your home. The broad term “fleas” typically refers to one of two species that tend to infest homes in North Carolina, the cat flea (Ctenocephalides felis) and the dog flea (Ctenocephalides canis). Both of these species can rapidly infest your home and be difficult to successfully eliminate. In this article we will teach you the “need-to-know” information on flea biology, risks to your home and health, how to prevent and identify infestations, and should you need it, how to effectively control and eliminate fleas from your home.

Fleas are an ectoparasite, meaning they live on or around and feed on a host, rather than living “in” a host like some parasites (think about tapeworms – these will come up later). Of primary concern for homeowners and pest management in North Carolina are two species of flea belonging to the genus Ctenocephalides, the cat flea (C. felis) and the dog flea (C. canis). Less common, but still occasionally seen in North Carolina is the Oriental rat flea (Xenopsylla cheopsis). Contrary to their names, they regularly parasitize and feed on a wide variety of mammals and have even been seen on birds. Fleas are holometabolous insects, meaning they go through a 4-stage lifecycle consisting of Egg, Larva, Pupa, and then Adult stages (Figure 1). Adult fleas (roughly 1/8 inches long) (Figure 2) are the most commonly seen life stage, as they are the blood-feeding stage, and actively seek out warm-blooded hosts. They are brownish-black in color, with laterally flattened bodies that allow them to weave through body hair and fur, have no wings, and a powerful jumping mechanism called resilin (like a rubber-band) that can propel them 8-19 inches forward, and 5-8 inches high through the air towards their host, roughly 200 times their body length in a single jump. Once adults have landed on their host, they rarely leave by choice, latching on and frequently feeding.

After taking their first bloodmeal fleas will mate, and then females can begin producing eggs as early as 2 days post-feeding, and they ramp up their egg production over the course of 9 days, reaching up to 27 eggs produced per day. This impressive number of eggs requires a lot of blood, and mature egg-laying female fleas can consume up to 15 times their weight in blood each day. Once produced, eggs are shed into the environment where they develop into larvae over the course of 3-4 days (Figure 1 & Figure 3). Once they emerge, larvae feed on organic debris found in the environment, such as pet dander and fur, and as such they typically live around pet bedding and furniture where food is plentiful (Figure 4). Once they have fully developed, typically 1-3 weeks depending on their host and environment, the larvae will form a sticky cocoon for protection while they develop into adults. These cocoons quickly become covered in debris from their environment, providing extra protection and camouflage (Figure 3). Fleas remain in the pupal stage for 1-2 weeks, and then emerge as an adult flea to find a host, beginning the cycle once again. It is important to note that adult fleas can lay dormant in the pupal stage for up to 5 months waiting for an unsuspecting host to walk by, with the vibrations produced by movement triggering a sudden emergence of the hungry adult fleas. This phenomenon regularly comes up in pest management when infested homes have been left vacant for months, and unsuspecting new tenants or realtors enter the home for the first time, ringing the dinner bell and suddenly being covered in hungry biting fleas.

Figure 1: The lifecycle of the flea, showing transition from egg, to larvae, to pupa, and then to blood-feeding adult.

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Figure 1: The lifecycle of the flea, showing transition from egg, to larvae, to pupa, and then to blood-feeding adult.

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Figure 2: An adult C. felis flea photographed from the side. You can see its six-legs, characteristic of all insects, and the absence of wings from its body.

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Figure 2: An adult C. felis flea photographed from the side. You can see its six-legs, characteristic of all insects, and the absence of wings from its body.

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Figure 3: An image of debris from a flea infested home with larva, pupa, and eggs denoted by red arrows. Debris can be seen attached to the sticky pupae, and multiple eggs are scattered throughout.

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Figure 3: An image of debris from a flea infested home with larva, pupa, and eggs denoted by red arrows. Debris can be seen attached to the sticky pupae, and multiple eggs are scattered throughout.

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Figure 4: A late-stage C. felis larvae with food digesting in its body (reddish-brown hue). Its head is located on the right side of the image, and spines (setae) can be seen along its entire body.

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Figure 4: A late-stage C. felis larvae with food digesting in its body (reddish-brown hue). Its head is located on the right side of the image, and spines (setae) can be seen along its entire body.

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Fleas are vectors of several pathogens, both to humans and animals, including the plague (in the case of the rat flea). All three species of flea can lead to infection with flea tapeworms if accidentally ingested, or if individuals come into contact with contaminated feces, in both humans and animals. The diseases and health risks of greatest concern associated with fleas, many of which can be found in both humans and animals, are:

1. Plague (Yersinia pestis) : A bacterial infection vectored through the bite of the Oriental rat flea (X. cheopsis) in areas with rodent populations actings as reservoirs for disease. In the United States this is most commonly seen in prairie dog populations, with only seven or so cases reported to the CDC annually (CDC).

2. Flea-borne Typhus (Murine Typhus): A bacterial infection which occurs when humans or animals are exposed to infected feces of the cat flea (C. felis) following a flea bite. Typically, infected feces is scratched into the open bite wound, leading to infection (CDC).

3. Bartonellosis (Cat-scratch fever): A bacterial infection caused by Bartonella genus bacteria, which often comes as a result of being scratched by a cat (as the name suggests) but can be vectored to humans from infected fleas (X. cheopsis, C. felis) (CDC).

4. Flea Tapeworm: A parasitic infection resulting from accidental ingestion of fleas or their feces that contain tapeworm eggs. This can occur in both humans (often in children) and in pets (as a result of grooming) (CDC).

There are several indicators of flea infestation:

Bites: Fleas feed on blood, and their bites can be painful and itchy, especially if they are feeding in large numbers. You may notice small red bumps on exposed areas of skin, typically on your lower legs, that are raised and itchy. You may notice increased scratching behavior by your pets, especially around the ears, shoulders, and area around the tail. Itchy bumps do not always mean that fleas are present in your home, and some pets have seasonal allergies which cause increased scratching, but these can be one of the potential indicators of flea infestation.

Feces: As fleas feed they also defecate (poop), and as it dries it becomes black and flaky. The feces can build up around bite sites, the base of hairs, and in your pet’s fur. It is easily disturbed and resembles a black dandruff in heavy infestations.

Insects: The clearest sign of an infestation is live insects, either the larvae (Figure 4), pupae (Figure 3), or adults (Figure 2). The larvae will often be seen in and around pet bedding, where there is an abundance of food. Pupae can also be found in these areas, or in the surrounding area as movement of pupae can occur due to their stickiness. Adults are far more mobile and can be found throughout infested homes, as they move to find a host. Adults are the most commonly seen life-stage and appear as small brown to black specks that will jump when disturbed. They are much easier to see against lighter colored backgrounds, such as white or cream clothing.

Fleas are vectors of several pathogens, both to humans and animals, including the plague (in the case of the rat flea). All three species of flea can lead to infection with flea tapeworms if accidentally ingested, or if individuals come into contact with contaminated feces, in both humans and animals. The diseases and health risks of greatest concern associated with fleas, many of which can be found in both humans and animals, are:

Avoiding a flea infestation begins with prevention, and much of this prevention revolves around your pets :

1. Pet Medication: It is important to keep your pets on a consistent flea preventative, either topically (e.g., PetArmor^TM or Bravecto^TM) or a systemic product taken as a pill or treat (e,g., Simparica Trio^TM). Both methods of application can provide excellent flea prevention when used as directed by your veterinarian. Always discuss new treatments with your vet before beginning them, as certain products and insecticides have been known to harm pets.

2. Bathing & Grooming: Regular grooming and bathing of your pets can help reduce the amount of pet dander and hair left in your home, reducing food sources for flea larvae. This will also help you identify fleas on your pets early, before they become a major problem.

3. Vacuuming: Regular vacuuming, especially in and around areas where your pets spend most of their time, can help cut down on food sources available to flea larvae. It can also remove up to 30% of flea larvae and 60% of eggs from your carpet if fleas are present (Texas A&M Extension).

Pet Bedding: Regular changing and cleaning of pet bedding can remove key food sources for flea larvae, and can also remove flea larvae, eggs, and pupae if they are present. This cleaning should include vacuuming, but also washing and drying as needed, which will also kill all life stages of fleas present in the bedding.

It is important to mention that even if you take all of the preventative measures we mention above, fleas can still appear in your home. Despite being called the cat flea, dog flea, and rat flea, they can feed on a wide variety of host mammals. Many homeowners live near or adjacent to greenspaces that are often frequented by wildlife, including rodents, raccoons, deer, and even stray pets. All of these and more can serve as potential introductions of fleas into your yard, under your house, into your walls (in the case of mice and rats), into your attic (in the case of birds), or directly to one of your pets through contact outdoors. In the event that this happens, there are some key steps you can take to successfully control fleas in your home:

1. Ensure your pet’s preventative treatments are up to date, as this will kill any adult fleas feeding on them and will kill fleas of any stage residing on their bodies.

2. Regularly bathe & comb your pets to mechanically remove any fleas not yet killed by the preventative method of your choice.

3. Deep clean or discard all pet bedding associated with the infested areas of the home, making sure to not reintroduce bedding until the problem is dealt with.

4. Vacuum your home extensively, discarding the bag or debris frequently, making sure that trash bags are sealed to prevent reintroduction in the home. Pay careful attention to:
   • Carpeted areas, especially those with thick carpeting.
   • Furniture and areas of carpet covered by furniture, especially those that collect large amounts of pet hair and dander.
   • Edges of rooms where carpets meet baseboards, creating crevices which are ideal areas for flea larvae and pupae to hide.

5. Essential oil-based products can provide some relief from adult fleas, especially products containing limonene and linalool which have both be shown to kill adult fleas. However, these are short-lasting products and should not be relied on alone for flea management.
6. Chemical insecticide treatments are an effective method of flea management and should always be performed by a pest management professional. Treatments should include areas within the home, as well as the yard around the home to eliminate flea populations residing outdoors. Discuss and develop a treatment plan with the pest control professional that will meet your specific needs. Prior to any treatments make sure to vacuum and remove all children’s and pet toys from the area to be treated. Also remove all pet bowls and food. These products can easily become contaminated if left in the treatment area.

Due to the nature of flea development and biology, follow-up treatments may be required to fully eliminate the infestation. Work with your pest management professional to develop a plan, but typically re-treatments are performed 5-10 days after the initial treatment, and as needed afterwards.

Disclaimer: Any commercial products mentioned in this publication serve as examples only, and do not represent endorsements of the products by any entities associated with this publication.