Public Health Vectors and Pests

Black Rat

Common Name Black Rat, Ship Rat, Roof Rat and House Rat

Scientific Name Rattus Rattus
Size Body length : 10-24cm
Weight : 150-200g
Colour Black in colour with a lighter coloured ventral belly.
  • Black rats are very similar in appearance to brown rats, but they are slimmer, with relatively larger ears and a longer tail.
  • Despite their name, they are typically grey brown, with a pale grey underside, but they may be completely black.
  • Outdoors: roof rats nest in high places such as trees, but sometimes in burrows under plants.
  • Indoors: they nest in high places in structures, but sometimes in basements, sewers, or under buildings.
  • Gestation 20-22 days
  • Weaning 21-28 days
  • Sexual maturity 3-4 months; total life may not exceed two years
  • The life cycle of rats is around a year to eighteen months, during which time, the female will typically breed up to six times, with the average litter being seven or eight.
  • Breeding occurs throughout the year, but especially in the spring or autumn
Disease Transmitted Plague: The bacterium(Yersinia pestis), Vectors(Oriental rat flea
Symptoms Plague:
  • development of high fever , headache, delirium
  • swelling of lymph glands
  • skin eruptions possible
  • secondary pneumonia possible

Types of Damage
  • Roof rats gnaw and eat stored food,
  • Transmit disease by droppings and urine, bites, and the fleas and mites in their fur.
Sources Breeding
  • Most breeding activity occurs from March to November, and they produce 3-5 litters a year.
  • Females give birth to 7-8 young after a gestation period of 23-24 days. They are weaned after 3-4 weeks
Prevention Rodent proofing your home
  • Repair or replace damaged ventilation screen around the foundation and under eaves.
  • Provide a tight fitting cover for the crawl space
  • Seal all openings around pipes, cables, and wires that enter through walls or the foundation.
  • Be sure all windows that can be opened are screened and that the screens are in good condition
  • Cover all chimneys with a spark arrester
  • Make sure all exterior doors are tight fitting and weatherproofed at the bottom
  • Seal gaps beneath garage doors with a gasket or weather-stripping
  • Keep side doors to the garage closed, especially at night

  • Concentrate control where most droppings are found.
  • Place traps and bait stations along runways, against vertical surfaces
  • Wire glue boards to rafters and pipes
  • Rats are cautious. Pre-baiting with non-toxic bait may be needed.
  • Rats are gluttonous. Use sufficient bait for 1, 2 or more meals baits. For roof rats use high-carbohydrate baits, liquid baits if water source can be eliminated. Burrows can be gassed.
  • If you use any baits, gas, or pesticide, be sure they are registered for this species, read entire label first, strictly adhere to all directions, restrictions, precautions

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