inaccessible spots that their total eradication is practically impossible. 

 So long as there are. large uninhabited areas, snakes wiLL continue to spread 

 from these centers .into settled districts., even though a constant .v;arf are 

 be kept up against them,. The -introduction of predatory animals.,, especially 

 the mongoose/ -no matter' of which sex, to combat them, ..is. never desirable . 

 because they will destroy at" lie^^st as many grouii4^ii*5 sting birds as they .' 

 will injurious animal-s*.. The- . importation of mongooses, is p>rohibited .by law. 



So far as knoiivh, only one method of eradipating snakes is generally 

 successful, and that is to kill- them by- clubbing or shooting. Local cam- 

 paigns for destroying such poisonous snakes as the cottonmouth moccasin, 

 the -capper head i- the rattlesn,ako.,. the massasauga, and the;, coral snake are 

 desirable in mrjiy districts. Kost of the nanpoisonous .snakes are distinct- 

 ly beneficial for their food consists to a large extent of injurious ro- 

 dents and; insects, and all campaigns against snakes should discriminate 

 between poisonous and. nonpoisanqus^ and .between harmful and usef^il, yar 

 rieties, _ .....,,., .:•..'.. ^^ , ., .:'.'. 



USE OF POISONOUS GAS^S \. . .• 



Snakes seem to be. immune to the effects of certain ..kinds of poisonous 

 gases, including phosgene, chlorine, and tear-, chemicals.- Tests conducted 

 in., a cave near S-an liar cos. Hays .County, Texas, approximately 50,. miles .north 

 of San Antonio, failed to produce -any .results when phosgene ..and chlorine 

 fumes were forced under pressure into the recesses of ,a rocky cave infested 

 with rattlesnakes. On the other hand, in the State of /ashington, v<-hen 

 mustard g,as was pumped into, the crevices, of a bed of , lava rock, rattle- 

 sn?J^es were driven out in a, d.azed condition and were- easily killed v/ith 

 clubs, " . . ; - 



Field employees of the -Fish and './ildlife Service have had much suc- 

 cess in destroying r.attlesnakes with crude calcium cyanide. It has been 

 found th.at 2 ounces of calcium— cyanide dust (about tv.'O: table spoonfuls) are 

 reciuired to kill- a rattlesnake "that has taken refuge in a ground-squirrel, 

 or prairie-dog burrow. The. cynnide should be placed well down in the burrow 

 by means of a ladle or long-handled spoon r^nd in a mass rather than scat-, 

 tered, A stone or piece of sod should be used to cover. the entrance ra- 

 . ther than soil, which might. Slide into the hole .-^Jid interfere with, the 

 formation of the g?.s.. .Under ordinary conditions a .snake vdli be killed by 

 about 3.0 minutes' exposure to the cyanide g?-?. • 



Calcium cyanide is a deadly poison. It should be kept in the origi- 

 nal air-tight container and out of reach of irresponsible persons, child-, 

 ren and. livestock. Small., quantities of cyanide may be carried to the 

 area to. bo treated in a c-in fitted with a tight top. .All handling of .the 

 material should . be. done in the open air,. 



The effectiveness of calcium cyanide gasing depends on relative hu- , 

 midity, for moisture in the air combining vdth the cyanide' liberates hy- 

 drocyanic-acid- gas,- which 'remains active in the burrow for several hours, 

 diffusing in all directions. Unsatisfactory results may be expected, how- 



- 8 - 



