How to check entry points

Insects may enter object spaces in a variety of ways. Insects themselves are very small, so finding all the gaps that may admit insects can be very difficult. Rats and mice can enter buildings through surprisingly small spaces – if a pen can fit into a gap, so can a mouse. They often have set routes into and around buildings and their regular passage can leave signs that can be easy to detect. Spaces that admit birds are usually easier to locate.

General checks

Start with the outside of the building.

  • Look at the roof – check for missing tiles, missing or lifted lead work, failed pointing on chimneys.
  • Check the chimney – does it have a cap? (Make sure that this is appropriate to the use of the chimney) Do you know where the fireplaces are that link to the chimneys? Have the chimneys been swept? If they are no longer in use, were they swept before the chimneys were closed off?
  • Check the gutters and downpipes – is there plant life growing in them? If so, they are blocked and the plants may be giving harbourage to insects.
  • Check windows, sash windows usually have large gaps which will allow insects to get in.
  • Look at the building structure – are there gaps around windows and doors? These may admit insects and other animals. Such gaps may also be roosting sites for bats. Consult a specialist if you suspect this, disturbing a bat roost is an offence.
  • Check the pointing of the building – is it sound?
  • Look for air bricks and ventilators, the holes may be large enough to let insects and rodents in.
  • Are there plants growing up the building? This may harbour insects or birds.
  • Look for pipes penetrating the structure. Gaps around these may admit insects or mice.
  • Look at the doors. Gaps beneath doors may admit insects and animals.
  • Look at what surrounds the building. Flower beds immediately next to the building may harbour insects and animals. Parks or gardens around the building will also harbour wildlife and may act as a reservoir of pests. Rubbish kept next to the building may act as a food source for pests, food rubbish will be particularly attractive to rats.


Continue with the inside
  • Check for fireplaces? Debris in the grate indicates that the chimney is not completely sealed. Consider sweeping and capping the chimney. If a board has been fitted inside the grate, remove it and check the chimney.
  • Check the floor. If the room has floor boards/floor vents a build up of dust in these spaces may be acting as a reservoir for insects. Vents may connect to the outside – these may admit mice.
  • Check the walls and ceiling for ventilators. These may admit insects or birds.
  • Check the room contents. New flower arrangements (live or dried) and plants may have brought insects in with them. Props are often unchecked before they enter collection spaces and may be the source of an infestation.


Narrow down the search
  • Use an increased number of blunder traps to try to pinpoint the main area of an insect infestation. Using a system of coloured dots on a floor plan to record the number and species of insect can help to narrow down the main area of the infestation.
  • Check carefully in this area to find out where the infestation has come from.
  • Track the signs of damage from rodents/birds/bats to try to find their entry point. Pest control specialists and Bat Groups have specialist equipment that can help.