Rats & Mice

SCIENTIFIC NAME:                  Rattus norvegicus (Berkenhout)

 

CLASS / ORDER / FAMILY:     Mammalia / Rodentia / Muridae

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INTRODUCTION

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The Norway rat is the largest of the commensal rodents and the most common commensal rat in the temperate regions of the world. It damages/destroys materials by gnawing, it eats and contaminates stored food and is also of human health importance as it is a carrier of diseases. It is thought to be of central Asian origin, but is now of worldwide distribution.

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DISEASES

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• Some transmittable diseases include:-

                  Ø   Murine typhus via fleas (also possibly via droppings and urine).

                  Ø   Infectious jaundice/leptospirosis/Weil's Disease via urine in water or food. 

                  Ø   Rat-bite fever via bites. 

                  Ø   Cowpox virus (CPXV) via direct contact.

                  Ø   Trichinosis via undercooked pork. 

                  Ø   Food poisoning or Salmonellosis via droppings.

                  

SIGNS OF INFESTATION

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• Gnaw marks. New gnawings or holes tend to be rough whereas, old gnawings are smooth from wear and old holes are often greasy.

• Droppings. Fresh droppings are soft and moist whereas, old droppings are dried and hard; adult Norway's about 3/4" (18-20 mm) with blunt ends vs. adult roof's about 1/2" (12-13 mm) with pointed ends.

• Tracks / footprints. Front foot 4-toed and print is in front of usually longer hind print with 5 toes. Fresh tracks are clear and sharp whereas, old tracks are at least par­tially obscured by dust.

• Rub marks or dark, greasy markings on vertical surfaces. Fresh marks are soft, greasy, and easily smeared whereas, old marks are with the grease dry and flaky.

• Burrows. Found in earthen banks, under concrete slabs, and under walls. If active, free of dust and cobwebs. Main opening usually with hard packed soil, rub marks may be visible.

• Runways. Consistently follow same paths, usually along walls, stacked merchandise, etc. Active runways with greasy appearance, free of dust and cob­webs, with fresh tracks and/or droppings.

• Damaged goods. Norway rats prefer meat, fish, and cereal (dry dog food a favorite) whereas; roof rats prefer fruits, vegetables, and cereals.

 

RECOGNITION

 

• Adult with combined head and body length 7-9.5" (18-25 cm), tail length 6-8" (15-21 cm), usual weight about 7-18 oz (200-500g) but up to 20.5 oz (620 g).

• Fur coarse, shaggy, brown with scattered black hairs, with underside gray to yellow­ish white.

• With muzzle blunt, small eyes and small ears.

• With scaly bicolored tail (darker above).

• Adult droppings up to 3/4" (20 mm) long, cap­sule-shaped with blunt ends.

 

BIOLOGY

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• Norway rats reach sexual maturity in 2-5 months.

• Pregnancy lasts an average of 23 days (range 21-25). The young/pups are blind and naked at birth. Hair appears in about 7 days and eyes open in 12-14 days.

• They have rather poor vision and are colour blind, but their senses of hearing; smell, touch, and taste are keenly developed. Touch is via their vibrissae or long whiskers.

• They are good runners, climbers, jumpers, and swimmers (documented record is 1,300 ft or 400 m across Open Ocean).

• A Norway rat requires ¾ - 1 oz (21-28 g) of food and ½ - 1 oz (15-30 ml) of water each day, with the water coming from a non-food source. This results in about 30-180 droppings and ½ oz OR 3 teaspoons (16 cc) of urine produced each day.

 

HABITS

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• Rats are primarily nocturnal in habit and they are cautious.

• Although they constantly explore their surroundings, they shy away from new objects and changes.

• Outdoors, Norway rats prefer to nest in burrows in the soil along railroad embankments, stream/river banks, piles of rubbish, under concrete slabs, etc.

• Norway rats usually nest in basements and the lower portions of buildings in piles of debris or merchandise as long as it is not disturbed.

• An opening of greater than 1/2" (12 mm) is required for entry into buildings.

• Norway rats are opportunistic feeders and although they will eat practically anything, they prefer meat, fish, and cereal.

• Norway rats will travel about 100-150 ft (30.5-45.7 m) from their harbourage for food and/or water; in urban areas the average home range is about 25-100 ft (8-30.5 m).

• They will gnaw through almost any­thing to obtain food and/or water, even plastic or lead pipes.

• Once established, Norway rats tend to follow the same route or pathway between their harbourage and food and/or water sources.

• Their runway path will be free of debris, and outdoors, the grass will be worn away to the bare soil.

 

CONTROL

Treatments are to be done by trained professional

 

• If any of the signs of damage / infestation are seen. Contact Rehoboth Ltd immediately 627 -0130 for FREE consultation to determine entry points and levels of infestation.

• The key to any rat control program is pest identification, sanitation, harbourage elimination, and rat-proofing the building. Control is based on the behavioural habits of the Norway rat.