• Rats have contributed to the death of more humans than all the wars and revolutions in history.
   
• The world-wide damage and destruction caused by rats and mice exceeds 200 billion dollars per year.
   
• Rats destroy 20 percent of human food supplies annually, enough food to eliminate world hunger.
   
• Rats carry more than 20 often-fatal diseases, including bubonic plague, dysentery, rabies, spotted fever and many more.
• Dangerous disease-carrying insects infest rats, including the flea, tick, louse, mite and mosquito.
   
• A rat can smell poison one part in one million and will urinate on the poison to warn other rats not to touch it.
   
• A pair of rats can potentially produce 620,000 descendants in only three years if left unchecked.
   
• Thousands of building fires of unknown origin are caused by rats gnawing insulation from electrical wiring.

Sanitation and Exclusion

Proper sanitation will do a great deal to control rodent pests. All animals have three requirements for life; food, water, and cover. Removal of any one will force an animal to leave. The removal of debris such as, piles of waste lumber or trash, used feed sacks, abandoned large appliances, and trimming the dead fronds from palm trees will substantially reduce the harborages for rodent pests. Stacked firewood stored for long periods provides good harborage for all rodents. Storage of pet food and seeds, such as wild bird seed, in rodent proof containers of glass or metal, will eliminate these food sources. Collect and remove fallen fruit from backyard trees and orchards. Keeping lids on trash cans and closing dumpsters at night will also make an area less attractive to rats and mice. The drainage holes in dumpsters should be covered with hardware cloth to keep rodents out.

Exclusion is also called rodent-proofing. This involves making your home a fortress that rodents can not breach. Rodents can squeeze through any opening that their head can fit through. That is a 1/4 inch opening for mice and a 1/2 inch opening for young rats. Young rats and mice are the dispersing individuals, so these are the ones most likely to invade new areas, like your home. Any opening that a pencil can fit through will admit a mouse.

Below is a list of recommended materials for excluding rats and mice.

• Galvanized, stainless, or other non-rusting metal.
  • Sheet metal, 24 gauge or heavier.
  • Expanded metal, 28 gauge or heavier.
  • Perforated metal, 24 gauge or heavier.
  • Hardware cloth, 19 gauge or heavier, 1/4 inch or smaller mesh.
• Cement mortar with a 1 part cement: 3 part sand mix or richer.
   
• Concrete with a 1 part cement: 2 part gravel: 4 part sand mix or richer. Broken glass added to mortar or concrete will deter rodents from tunneling through a  patched hole before the material hardens.
   
• Brick, concrete block, tile, or glass will exclude rodents if in good repair.
   
• Wood will exclude rodents if no gnawing edges are present.