FUMIGATION 287 



the trunk ; cover this with a strip of tarred paper five inches wide ; 

 draw the paper tight and fasten at the lap only with three or four 

 tacks. Spread the tanglefoot on the upper two-thirds of the paper, 

 and comb it from time to time to keep the surface sticky. 



Burlap bands are made by tying or tacking a strip of burlap 

 around the trunk and letting the edges hang down. The larvas 

 will hide under the loose edge, where they may be killed. 



Banding is now little used for the codlin-moth, since spraying 

 with poison has been found so much more effective. 

 Fumigation. — Fumigating or " smoking " or " smudging " in green- 

 houses is performed by the slow burning of tobacco-stems. Best 

 results are obtained when a sheet iron vessel made for the purpose 

 is used, having holes in the bottom to supply draft. A quart 

 of Uve coals is placed in the bottom of the vessel, and about a pailful 

 of tobacco-stems is laid on them. The stems should not blaze, 

 but burn with a slow smudge. If they are slightly damp, better 

 results are obtained. Some plants are injured by a very heavy 

 smoke, and in order to avoid this injury, and also to more effec- 

 tually destroy the insects, it is better to smoke rather lightly and 

 often. It is always well to smoke on two consecutive days, for the 

 insects which persist through the first treatment, being weak, will 

 be killed by the second. If the plants are wet, the smoke is more 

 hkely to scorch them. The smudge often injures flowers, as those 

 of roses and chrysanthemums. In order to avoid this injury, the 

 flowers should be covered with paper bags. Tobacco fumes can 

 be conveniently generated by burning strips of prepared nico- 

 tine paper, or by vaporizing a concentrated aqueous solution of 

 nicotine in pans over alcohol or special kerosene lamps. 



Fumigation with hydrocyanic acid gas. — Hydrocyanic acid gas 

 is a deadly poison, and the greatest care is required in its use. Al- 

 ways use 98 to 100 per cent pure potassium cyanide and a good 

 grade of commercial sulfuric acid. The chemicals are always com- 

 bined in the following proportion : Potassium cyanide, 1 ounce ; 

 sulfuric acid, 1 fluid ounce ; water, 3 fluid ounces. Always use an 

 earthen dish, pour in the water first, and add the sulfuric acid to 

 it. Put the required amount of cyanide in a thin paper bag, and 

 when all is ready, drop it into the liquid and leave the room 

 immediately. For mills and dwellings, use one ounce of cyanide 



