been unsuccessful. It is a simple 

 procedure, and the extra time thus 

 spent is well worthwhile. 



All sources of food for rats 

 should be removed, particular at- 

 tention being given to such items 

 as garbage cans, stored foods, 

 grain bins, and exposed crates 

 of fruits and vegetables. Trash, 

 piled materials, or other nonfood 

 items should be left where they 

 are until after the baiting has 

 been completed. Runways or bur- 

 rows should not be blocked, as this 

 might arouse the suspicion of the 

 rats or cause them to move. 



It is best to use at least three 

 kinds of food baits so selected as 

 to give the rats a choice of moist 

 or dry foods. The following 

 classes, many of the items of 

 which may be obtained from or- 

 dinary kitchen scraps, are sug- 

 gested: 

 Meat: Ground lean beef, beef 



melts, liver, sausage, bacon, 



chicken entrails, or canned 



meat. 

 Fish: Fresh ground raw fish, 



canned fish, or cat food. 

 Cereals: Bread crumbs, rolled 



oats, corn meal, or chicken 



mash. 

 Vegetables: Sliced tomatoes, 



green corn, carrots, or lettuce. 

 Fruits: Cantaloups, watermelons, 



bananas, or apples. 

 Miscellaneous : Peanut butter, 



sweet chocolate, dried milk, or 



raw eggs. 



Expose the different kinds of 

 bait to be tested in teaspoonful 

 quantities side by side in all spots 

 where rats may be likely to feed 

 upon them. Place baits late in the 

 afternoon or early in the evening, 

 treating the entire area to be cov- 

 ered. Protect the baits from in- 

 terference by cats, dogs, or per- 

 sons. Observe the results the 

 following morning, noting the 

 most acceptable bait, locations 

 wlier^ the bait was taken, and the 



quantity of bait consumed. The 

 exact locations of the most fa- 

 vored baits should be noted care- 

 fully, as it is there that the poi- 

 soned baits should be placed later. 

 Remove all uneaten baits. If no 

 baits should be taken readily, 

 skip two nights and then repeat 

 the operations with other baits 

 until an attractive one is found. 



When the most acceptable bait 

 has been determined, continue the 

 prebaiting with this material for 

 two or three nights in succession 

 to accustom all rats to baits and 

 locations before adding the poison. 

 Be sure to place the poisoned baits 

 in the same spots as the accepted 

 prebaits. 



USE OF POISONOUS GASES 



Control of rats by means of 

 poisonous gases includes the fu- 

 migation of buildings and struc- 

 tures, and the gassing of burrows. 

 The fumigation of buildings re- 

 quires considerable preparation 

 and special techniques. It should 

 be attempted only by persons 

 trained for such work, and in 

 many areas the use of poisonous 

 gases is controlled by local regu- 

 lations. In view of the many haz- 

 ards and complications involved, 

 its use in rat control, except by 

 professionals, is not generally 

 recommended. 



The gassing of rat burrows out- 

 of-doors is an excellent means of 

 control (fig. 3). Many rats are 

 destroyed under ground, so there 

 is no problem of the disposal of 

 the carcasses. Gas has the advan- 

 tage over poisons of destroying 

 the flea and mite parasites as well, 

 a factor of considerable impor- 

 tance in controlling the spread of 

 some diseases. 



The gas most commonly used in 

 rat control is calcium cyanide, in 

 a dust or finely powdered form. 

 It is easily exposed by means of a 

 foot, or stirrup, pump, designed 



