Signs You Have a Pest Problem

Pest infestations rarely start with something dramatic. More often, it's a small clue — a few droppings behind the fridge, an odd scratching noise at night, or an unexplained rash — that turns out to be the tip of a much larger problem. The sooner you identify the signs, the easier and cheaper the problem is to solve. We've spoken to pest control professionals across England to compile the most reliable indicators that something has moved in.

Rodent Signs: Rats and Mice

Rodents are the most common pest in UK homes, particularly during autumn and winter when they seek warmth and food. Here are the telltale signs:

Droppings

Rodent droppings are the single most reliable indicator. Mouse droppings are small (3–8mm), dark, and roughly the shape of a grain of rice. Rat droppings are larger (10–20mm), darker, and more capsule-shaped. Check behind kitchen appliances, inside cupboards, along skirting boards, and in loft spaces. A single mouse can produce 50–80 droppings per day, so even a small number suggests recent activity.

Gnaw Marks

Rodents must constantly gnaw to keep their teeth worn down. Look for tooth marks on food packaging, wooden skirting boards, plastic containers, and electrical cables. Fresh gnaw marks are light in colour and become darker with age. Gnawed electrical wiring is a serious fire risk — if you spot it, call a professional immediately.

Scratching and Scurrying Noises

Mice and rats are most active between dusk and dawn. Scratching sounds from the loft, behind walls, or under floorboards — especially at night — are a strong indicator. Rats tend to produce heavier, slower sounds; mice are lighter and faster. If you hear noises in the loft, it could also be squirrels, which are active during daylight hours.

Nesting Material

Rodents build nests from shredded paper, fabric, insulation, and other soft materials. Check loft spaces, behind appliances, inside storage boxes, and under garden sheds. If you find a nest, the infestation is established and likely involves multiple animals.

Grease Marks and Runs

Rats follow the same routes repeatedly, leaving dark grease marks (from their oily fur) along walls, pipes, and beams. These smear marks are most visible along skirting boards and around entry holes. If the marks look fresh and smudge when touched, the rats are still active.

Insect Signs

Bed Bugs

Bed bugs are notoriously difficult to spot because they hide during the day and feed at night. The first sign is usually bites — small, red, itchy welts that appear in clusters or lines on exposed skin, typically on arms, shoulders, and neck. Other signs include:

• Tiny dark spots on mattress seams, bed frames, and headboards — these are bed bug faecal stains.
• Shed skins (translucent, pale husks) near sleeping areas. Bed bugs moult five times before reaching adulthood.
• A sweet, musty odour in heavily infested rooms, caused by the bugs' scent glands.
• Small blood spots on sheets or pillowcases from crushed bugs during the night.

Cockroaches

Cockroaches are nocturnal, so seeing one during the day usually means the infestation is significant and they're being pushed out of hiding by overcrowding. The two most common species in UK homes are the German cockroach (small, light brown, found in kitchens) and the Oriental cockroach (larger, dark brown or black, found in basements and around drains).

Other signs include a strong, unpleasant musty smell, dark smear marks along walls and surfaces where they travel, and egg cases (oothecae) — small, dark brown capsules about 8mm long, often found in crevices, behind appliances, or inside cupboards.

Wasps

A single wasp indoors isn't necessarily a problem, but if you're seeing multiple wasps entering and leaving from a specific point on your property, there is almost certainly a nest nearby. Common nest locations include loft spaces, wall cavities, under eaves, in garden sheds, and in the ground. Wasp nests start small in spring (golf-ball sized) and can grow to the size of a football or larger by late summer.

Ants

Ant trails — lines of ants marching between a food source and their nest — are unmistakable. In UK homes, the most common species is the black garden ant. They typically enter through cracks in walls, gaps around doors, or where pipes pass through external walls. While ants aren't a health risk, they can contaminate food and are difficult to eliminate once established.

Fleas

Flea bites appear as small, red, intensely itchy dots, usually around the ankles and lower legs. You may also spot tiny dark specks (flea dirt — essentially dried blood) on pet bedding, carpets, or soft furnishings. The quickest test: lay a white sheet or pillowcase on the carpet overnight. If you see tiny dark dots on it in the morning, you likely have fleas.

When to Act

The golden rule with pests is: act early. Every pest on this list breeds quickly, and what starts as a minor nuisance can become a serious infestation within weeks. Here's a simple guide:

• Ants or a single mouse. You can try DIY methods first. Shop-bought traps and bait stations may resolve the problem if you catch it early.
• Rats, wasps, bed bugs, cockroaches. Call a professional. These pests are either dangerous (wasps, rats), extremely difficult to eliminate without professional equipment (bed bugs), or both (cockroaches). DIY attempts usually waste time and money.
• Fleas. If you have pets, treat them first with a vet-recommended product. If the infestation persists or you don't have pets (suggesting the previous occupant or visiting wildlife brought them in), call a professional for a whole-house spray.

Health Risks

Pests aren't just a nuisance — several pose genuine health risks:

• Rats and mice can spread leptospirosis (Weil's disease), salmonella, and hantavirus through their urine, droppings, and nesting material. They also carry fleas and ticks.
• Cockroaches carry bacteria including E. coli and salmonella. Their droppings and shed skins are a known trigger for asthma, particularly in children.
• Wasps can sting multiple times, and for people with allergies, a single sting can cause anaphylaxis — a life-threatening reaction requiring immediate medical attention.
• Bed bugs don't transmit disease, but their bites cause significant discomfort, sleep disruption, and in some cases secondary skin infections from scratching.
• Fleas can transmit tapeworm (mainly to pets but occasionally to children) and their bites cause allergic reactions in some people.

If you're seeing any of the signs described in this guide, don't wait for the problem to get worse. Check our guide on pest control costs to understand what treatment typically costs, and compare rated companies in your area.