TUK OOMMON OU N()K\\A^ l^\T. 



493 



TIk! v'div. of increase is very rapid. The [)eri()d. of gestation is 

 short, and the female produces from four to twelve young three or 

 four times a year. Females begin to breed when only four or five 

 months old, and the potential number of descendents from a single 

 pair of parents within twelve months may be computed at 700 or 

 more, although the actual number is always much less. 



In addition to destroying a large amount of valuable commodi- 

 ties, rats are known to spread disease. It is not improbable that 

 they may sometimes spread tuberculosis, and infecticm of the bu- 

 bonic plague has been directly traced to these rodents. 



Methods of Destruction. — Rats may sometimes be captured by 

 setting steel traps in their holes or paths and covering them v^ith 

 loose dirt, but the animals often escape by sacrificing a foot. Wire 

 cage traps are sometimes effective and may capture several in a 

 night. They are shrewd animals, however, and those that live to 

 maturity become adepts in avoiding traps. The newer styles, which 

 consist of a v^ood or metal base, to v^hich is attached a loop of 

 stiff v^^ire driven by a coiled spring, are the most effective. Dry 

 oatmeal, cheese, sausage (especially ''v^iener wurst") or buttered 

 toast, make excellent baits. 



The United States Department of Agriculture has issued a bul- 

 letin dealing v^ith methods of destroying rats from v^hich the fol- 

 lowing facts are taken : 



One of the most effective means of destruction is the use of 

 barium carbonate or barytes. This is a mineral poison without taste 

 or smell and, in small quantities, is harmless to larger animals. 

 Its action is slow and the rodents usually leave a building to seek 

 water and their bodies do not, therefore, decay about the premises 

 and produce the offensive odors which make other poisons so ob- 

 jectionable. 



It may be made into a dough, using one-fifth barytes and four- 

 fifths cornmeal, or one-eighth barytes and seven-eighths oatmeal; 

 or it may be spread on bread and butter or moistened toast. The 

 poisoned bait should be dropped into the rat runs in small quanti- 

 ties. If it is not at once effective it should be tried again with an- 

 other bait. 



Strychnine and arsenic are also effective poisons, and the dry 

 powder can be put into sausage, cheese or raw meat; or it may be 

 dissolved in boiling water, with sugar added to kill the bitter taste, 

 and the sirup may then be mixed with oatmeal or poured on bread, 

 or wheat or corn can be soaked in it over night. The objection 

 to strychnine is that it is so virulent that rats die on the premises 



