It can be a major pest on some farms, where warmth, food and a source of water are easily found. Like the House Mouse, this animal is nocturnal, but the Brown Rat is very wary of new objects and is said to be neophobic (fear new things). A single Brown rat may produce up to 40 droppings in 24 hours so the contamination potential of these animals is high.
Brown rats are capable of carrying several diseases, amongst which, in the UK, are Salmonella food poisoning and Weils disease (Ieptospiral jaundice).

A mouse can produce up to 80 droppings in 24 hours, so food and food preparation surfaces can easily become contaminated even when only a small number of mice are present. Probably the most important disease that can be transmitted by mice in the UK is Salmonella food poisoning.

Wasps build elaborate nests made from a papery substance. Nests can be located hanging from trees, bushes and hedges, or beneath roof tiles, in attics, garages, etc. A wasp nest survives only for that season as the nest dies off in the late autumn, and although they will never re-inhabit an old nest, they may build a new one directly beside an old nest. At the height of the season, there may be as many as 25,000 wasps in a very large nest!

The Black garden ant is to be found throughout the UK, particularly where soil is of a sandy nature. It is common around homes and the workplace, the worker ants

entering through cracks in brickwork and around windows in search of food. These ants follow trails, so when a rich source of food is found, this information is communicated back to the nest resulting in large numbers of ants following a trail from the nest back to the food source. Nest openings can be distinguished by small piles of fine earth.

The cat flea (Ctenocephalides felis) causes most flea infestations. The significance of this is explained by the increased number of pets being kept and the tendency for their beds to be neglected during cleaning. Wall to wall carpeting also provides a relatively undisturbed environment for flew larvae to develop. Fleas are objectionable because of the bites they inflict and because of the social stigma attached to humans with flea infestations. Flea bites are identified as a tiny dark red spot surrounded by a reddened area. The intensely irritating bite persists for one or two days.

This makes infestations of the Common cockroach difficult to control, as getting insecticide to the harborages can be difficult, if not impossible. These pests can be found almost anywhere, from kitchens to cellars, in wall cavities, around fire places, in rubbish dumps and virtually any work environment. These insects are often confused with ground beetles.