How long do fleas take to clear?

Adults die quickly, but expect two to three weeks of reducing activity as protected pupae hatch into treated carpet. That is normal, not treatment failure.

Do I need to treat my pet too?

Yes — the property and the animal must be treated together, otherwise the cycle simply restarts.

Why am I getting bitten with no pet in the house?

Usually dormant pupae left by previous occupants, or fleas dropping from wildlife in a loft or sub-floor void.

What do I need to do before you arrive?

Vacuum thoroughly, clear floors, and wash pet bedding. We'll send a full preparation sheet when you book.

Is the treatment safe for children and pets?

Yes, once the surfaces are dry and the short exclusion period we specify has passed.

HPE Species Library

Cat flea

Ctenocephalides felis

Responsible for the overwhelming majority of UK household flea infestations — including in homes with no pets at all.

01727 601 007 Identify my pest

Quick facts

Adult size: 1.5–3.5mm
Eggs per day: Up to 50
Adults in a population: ~5%
Pupal dormancy: Up to months

Also known as: Household flea

Species at a glance

Moderate risk

Scientific name: Ctenocephalides felis
Alternative names: Household flea
Average size: 1.5–3.5mm adult
Average weight: Under 1mg
Activity: Both day and night
Diet: Blood. Larvae feed on organic debris and adult flea faeces in the carpet rather than on a host.
Typical habitat: Carpets, rugs, pet bedding and upholstered furniture
Active season: Late summer into autumn, indoors year-round

Why the moderate risk rating: Irritating bites to ankles and legs; tapeworm vector in pets.

About the cat flea

Despite the name, the cat flea infests cats, dogs, foxes and people alike. Adults are only a small fraction of the population: the majority of an infestation exists as eggs, larvae and pupae in carpet, bedding and floor cracks. Pupae can lie dormant for months and hatch in response to vibration and carbon dioxide — which is why empty properties can suddenly become infested when someone walks in.

Diet: Blood. Larvae feed on organic debris and adult flea faeces in the carpet rather than on a host.
Breeding: A female lays up to 50 eggs a day. In a warm home the full cycle completes in as little as 2–3 weeks.
Lifespan: Adults typically several weeks on a host; pupae can survive dormant for many months.

How to identify it

1.5–3.5mm, dark reddish-brown, laterally flattened
No wings; jumps up to 200 times its own body length
Larvae are small white worm-like grubs found deep in carpet pile
Flea dirt is black specks that turn rust-red on damp tissue

Signs, behaviour and where they live

Signs of activity

Itchy bites, usually clustered around ankles and lower legs
Pets scratching, biting at the base of the tail or losing fur
Black flea dirt in pet bedding that turns red when damp
Small dark insects jumping from carpet when disturbed
Sudden bites on returning to a property after a period away

Behaviour

Adults spend most of their time on the host, feeding several times a day
Only around 5% of the population is adult — the rest is immature stages in the environment
Pupae are protected by a sticky cocoon that resists insecticide
Dormant pupae hatch in response to vibration, warmth and CO₂

Where you'll find them

Carpet pile, rugs and floorboard gaps in rooms pets use
Pet bedding, sofas and the base of upholstered furniture
Skirting junctions and beneath radiators
Lofts and voids where foxes, squirrels or birds have nested

Seasonal activity in Hertfordshire

Twelve-month activity profile for cat fleas, based on our Hertfordshire call-out records.

LowModerateRisingHigh

January: Low activity
Jan
February: Low activity
Feb
March: Moderate activity
Mar
April: Moderate activity
Apr
May: Rising activity
May
June: Rising activity
Jun
July: High activity
Jul
August: High activity
Aug
September: High activity
Sep
October: Rising activity
Oct
November: Moderate activity
Nov
December: Low activity
Dec

Peak period: July to October
Right now: High activity in August

Warm, humid conditions accelerate the life cycle, and central heating in autumn triggers mass emergence of dormant pupae.

Hertfordshire Pest WatchElevated

Fleas are in their most active period of the year. Warm, humid conditions accelerate the life cycle, and central heating in autumn triggers mass emergence of dormant pupae.

Activity appears steady

Current local data is limited. The status shown is based primarily on established seasonal behaviour across Hertfordshire. Last reviewed 1 July 2026.

See all Hertfordshire Pest Watch activity

Why cat fleas matter

Health risks

Flea allergy dermatitis in pets and people
Secondary infection from scratched bites
Tapeworm transmission to pets that swallow fleas while grooming

Property damage

No structural damage — impact is health, comfort and, in lettings, void periods

Hertfordshire context

Cat fleas across Hertfordshire

Flea call-outs across Hertfordshire spike in late summer and again with tenancy changeovers, when new occupants trigger months of dormant pupae in carpets left by a previous pet.

Setting the record straight

Common misconceptions

No pets means no fleas.

Fleas arrive with previous occupants, visiting animals or wildlife in the loft, and dormant pupae outlast the pet by months.

Treating the pet clears the house.

Roughly 95% of the population is in the carpet, not on the animal. Both must be treated together.

One treatment fixes it.

Insecticide cannot penetrate the pupal cocoon, so a follow-up is normally needed as protected pupae emerge.

Prevention and professional treatment

How to prevent them

Maintain year-round veterinary flea treatment for all pets
Vacuum carpets, edges and under furniture frequently — vibration triggers pupal hatch
Hot-wash pet bedding weekly
Proof lofts and voids against foxes, squirrels and nesting birds

How we treat them

Confirm species and identify the source, including any wildlife harbourage
Preparation brief: thorough vacuuming and clearance of floor areas
Residual insecticide treatment to all floor areas, edges and soft furnishings
Instruction to keep vacuuming to trigger and expose emerging pupae
Follow-up treatment where dormant pupae continue to hatch

Treatments for cat fleas

Insect control

Residual flea treatment for homes, lettings and commercial premises.

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Pest identifier

Upload a photo for indicative identification before you book.

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Cat flea questions, answered

The questions our technicians are asked most often about cat fleas in Hertfordshire.

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Ask anything about the cat flea

This assistant is reading the cat flea profile with you — there's no need to say which pest you mean. Answers are educational and evidence-based.

Questions are recorded anonymously so we can improve HPE Knowledge. No personal data is stored.

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Helpful next steps

Professional treatment

Speak to a technician about cat fleas at your property. Fixed price confirmed after a brief inspection.

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View evidence gallery

Labelled field photography showing exactly what the signs look like in a real property.

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Browse the Treatment Library

Documented case studies from treatments carried out across Hertfordshire.

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Put a question directly to our cat flea assistant and get an evidence-based answer.

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Confirm we cover your town, village or postcode and see local activity.

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Contact Hertfordshire Pest Experts

Prefer to talk it through? Call the team or send the details of what you have found.

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Or head back to the HPE Species Library to compare species.