Bishop Miller Environmental Website


There are two pest species of rat commonly encountered in the UK; black rats (rattus rattus) also known as the roof rat or ship rat and brown rats (rattus norvegicus) also called the wharf rat or sewer rat. Both species are serious pests and infestations should be taken seriously and eradicated as soon as possible.

Black rats (above left) originated in South East Asia and spread along trade routes reaching Europe in the 6th century. They are now less common in cooler areas having being supplanted by the brown rat. Black rats grow to approximately 15 to 20 cm in length with the tail extending a further 20cm. Despite their name they are not always black ranging from light brown through to black usually with a paler coloured underside. They are nocturnal and omnivorous but have a preference for fruit and grain. Due to their evolution in forested areas they are extremely agile climbers and can only be prevented from climbing by using smooth surfaces such as metal plate. Fleas carried by infected black rats carried the bubonic plague, the Black Death, across Europe causing widespread loss of life in the 14th, 17th and 18th centuries.

Brown rats (above right) originated in Central Asia or China and also spread along trade routes reaching Europe by the 16th century. Brown rats grow slightly larger than black rats reaching a length of 25cm with the tail adding a further 25cm. They are usually dark brown or grey in colour with a paler underside. They are usually nocturnal and are omnivorous with a diet ranging from dried grain to live birds including poultry. They are very intelligent and adaptable and have demonstrated social learning of food gathering skills.


Rats can spread the following diseases either directly or via parasites such as fleas; Haemorrhagic Fever, Leptospirosis (Weil's disease), Lyme Disease, Murine Typhus,  Plague, Rat Bite Fever, Relapsing Fever, Salmonellosis, Scrub Typhus, Tularemia and many others.

Diseases vectored by rats

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