The black rat is blue grey to black in colour. The abdomen are lighter to yellow white. There are colour varieties as well (Alexandrian rat). The animal has a tender build with a pointy snout with large eyes and ears. The tail is considerably longer (20 – 25 cm) than the body (15 – 23 cm). The weight of an adult black rat is about 150 -250 grams.
Black rats are still very common. They are great climbers, which is whey they are common in high buildings. They feed on many products, with a preference for grains, seeds and fruit.
They have a rapid development; the females reach sexual maturity after about 3 months and can have up to 10 birth cycles with 6 – 10 young each in a period of 2 years. The average life expectancy is 2 years.
As described above, this rat species prefers to be in the immediate vicinity of people and their buildings, supplies and waste. Black rats are notorious spreaders of diseases; the plague in the Middle Ages was transmitted to people by rats and their fleas. They can also transmit various diseases in intensive livestock farming. They contaminate and damage supplies and because of their urge to gnaw (for instance cables) they can cause short circuit, leakage and machine failure. For that reason, black rats are undesirable in the direct vicinity of people.
Proper architectural provisions, such as properly closing doors, narrow ventilation openings, one can keep rats outside. Good hygiene (storage and removal of waste, tidy storage of products, regular cleaning of areas etc) is important to prevent the presence of rats.
After a thorough inspection of and around the object, bait depots are installed at strategically chosen places. In these bait boxes or crates, toxic bait is placed. The rodenticides used, approved by the Dutch College Toelating Bestrijdingsmiddelen are so called anticoagulantia (anti-clotting agents). These various toxic substances are available as ready to use bait or in the form of liquid concentrates. With the help of these liquid substances, PPD exterminators compose the most appealing bait, suitable for application under specific circumstances. These baits should be offered at least several weeks to cause death. After 2 to 7 days of absorption, death occurs after 7 to 14 days.
A preventive approach, being frequent inspection of the terrain, building and stored products, can prevent issues. Always pay attention to the architectural state of the object and the hygiene in general.