Autumn Pest Checklist: How to Protect Your London Home Before Winter

September and October are the busiest months of the year for pest control callouts in London. As temperatures drop, rats and mice begin actively seeking warmth indoors — and London properties, particularly older housing stock, offer plenty of entry points.

This checklist covers what to check and what to do before winter to reduce the chances of a pest problem.

Why Autumn Is High-Risk

Rodents don’t hibernate. As outdoor temperatures drop and natural food sources become scarcer, rats and mice become more active in seeking sheltered, warm harbourage — which often means the void spaces inside houses: cavity walls, loft insulation, under floorboards.

The shift happens quickly. Most pest controllers see a significant increase in rodent callouts from mid-September onwards, with a peak in October and November.

Wasps are also more aggressive in late summer and autumn as colonies begin to die off and individual workers are less controlled by colony behaviour.

Exterior Check: What to Look For

Walk around the outside of your property and check for:

Gaps around pipes and cables: Every point where a gas pipe, electricity cable, or water pipe enters the building is a potential entry point. Even a 12mm gap (the width of a pound coin) is sufficient for a rat; 6mm for a mouse.

Air bricks: Damaged or blocked air bricks are common in Victorian and Edwardian properties. Solid-sided replacements or galvanised wire mesh covers prevent rodent entry while maintaining ventilation.

Pointing and brickwork: Cracked or missing mortar creates gaps, particularly at damp-proof course level. Repointing affected areas is a structural fix but also a pest prevention measure.

Roof level: Check where fascia boards meet the roof — gaps here allow rats and squirrels direct access to the loft. Squirrels in particular are agile enough to access through small roof-level gaps.

Drain covers and inspection chambers: Ensure all drain inspection covers are intact and seated correctly. Rats are excellent swimmers and can enter properties through broken or open drainage.

Compost heaps and log piles: These provide both food and shelter for rodents. Keep compost heaps in rodent-resistant bins with solid bases, and store log piles away from the house if possible.

Interior Check

Once you’ve checked the exterior, go inside and look for:

Under kitchen units: The most common location for mice to enter — gaps where pipes pass through the kickboard or floor. Stuff any gaps with wire wool (temporary) or seal with expanding foam and mortar (permanent).

Behind appliances: Mice particularly like the warmth behind fridges, dishwashers, and washing machines. Check for droppings.

Loft hatch: Ensure it seats properly. An ill-fitting loft hatch allows access from the loft to the rest of the house.

Under floorboards: If you have access via loose boards or a crawl space, check for droppings or gnaw marks.

Garden and Outbuildings

Bird feeders: Ground-feeding birds or spillage from hanging feeders creates a food source for rats. Switch to squirrel/rat-proof feeders, or stop feeding entirely during peak rodent season (October–March).

Outbuildings and sheds: Regularly used spaces are less likely to become pest harbourage. Rarely-visited outbuildings should be checked and sealed where possible.

Decking: The void under decking is ideal rat harbourage — sheltered, dark, and difficult to access. Use decking that sits directly on a membrane or install a rat-proof mesh barrier around the perimeter.

Signs You Already Have a Problem

If you find any of the following during your check, act immediately:

• Droppings: Rat droppings are 10–20mm, dark brown to black. Mouse droppings are 3–7mm, rice-sized.
• Gnaw marks: On wood, cables, pipes, or food packaging
• Runs: Worn paths through grass, grease marks along walls (from rats’ oily fur)
• Nesting material: Shredded paper, insulation, or fabric in corners, under insulation, or in box rooms
• Sounds: Scratching or scrabbling in walls or ceiling at night

What to Do if You Find Evidence

Don’t delay — rodent populations can double in weeks under good conditions. Contact a professional pest controller rather than relying on DIY products, particularly if you’re seeing evidence of rats (as opposed to mice).

We offer same-day pest control across all 33 London boroughs. Our BPCA-accredited technicians will identify the species, implement the appropriate treatment, and survey for entry points. Get a quote online.

Seasonal Maintenance Summary

Check	Frequency	Priority
External gaps and pipe penetrations	Annually (autumn)	High
Air bricks	Annually	Medium
Drain covers	Annually	High
Bird feeders (switch to pest-proof)	October	Medium
Under-decking inspection	Annually	Medium
Loft insulation check	Annually	Low