Pest Control
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Many pest problems are smelled before they are seen. A smell that cleaning does not shift, or that keeps coming back in the same place, usually has a cause, and the type of smell is a good clue to what that cause is. Here are the common ones.
Sickly sweet and rotten: something has died
The smell of a decomposing animal is hard to mistake: heavy, sweet, sour and stronger than a drain or a bin. Indoors it is most often a rat or mouse that has died in a wall cavity, under a floor or in the loft, though birds in chimneys and other small animals are possibilities too. The smell can travel along voids and pipe runs, so it may seem to move from room to room.
It fades over a few weeks, but a carcass draws flies, and a sudden cluster of bluebottles at one window is a common follow-up. Our guide to dealing with dead rodents covers how long the smell lasts and how to deal with it safely.
Sharp ammonia: rodents living nearby
Rodent urine gives off a sharp, ammonia-like smell that is strongest in enclosed spaces such as lofts, cupboards, under-stairs spaces and the voids behind kitchen units. Mice also leave a stale, musky smell. Together with droppings, they point to rodents that are alive and using the space regularly, and the stronger the smell, the longer they have usually been there.
This smell calls for finding where the rodents are living and how they are getting in, not just cleaning where the smell is.
Oily and musty: cockroaches
A heavy cockroach infestation has an oily, unpleasant, musty smell that clings to the area around their harbourage: behind cookers and fridges, around warm pipework and in ducting. By the time you can smell them, the numbers are usually significant.
Sweet and musty in a bedroom: bed bugs
Heavily infested rooms can have a sweet, musty smell. Most bed bug problems are found well before that stage, from bites, blood spots on bedding or dark specks along mattress seams, but an unexplained smell in a bedroom alongside any of those is worth checking.
Stale and dusty in the loft: birds
Nesting birds in a roof space leave droppings, feathers and old nesting material, which build up into a stale, dusty smell. The debris can also harbour mites and insects. It should be cleared with dust suppression, not swept up dry.
Musty and earthy: damp
A musty, earthy smell is usually mould and damp rather than pests. It still matters, because damp attracts pests of its own: woodlice, silverfish and mould mites all follow moisture. Fixing the leak, the condensation or the ventilation is what makes the difference. Our guides to woodlice and mould mites explain more.
Tracking down the source
- Note where and when. Is it worse in the morning, in warm weather, or after the heating comes on? Is it strongest near a wall, a cupboard or a ceiling?
- Look for other signs. Droppings, gnawing, smear marks, flies at one window or damp patches all narrow it down.
- Rule out the obvious. Drains, bins, the fridge, behind appliances and the washing machine seal can all produce bad smells.
- Do not pull up floors or cut into walls on a hunch. Smells travel, and the source is not always where the smell is strongest.
When to call us
Call us if a smell will not go away and you suspect rodents, cockroaches or something that has died, or if you cannot tell what it is. We trace the source, deal with it and, where there is an infestation behind it, treat it and close the way in. Our rat control page explains how we work.