THE MONTHLY BULLETIN. 319 



For storehouse Pests.— Before fumigation is begun care should be 

 taken to see that the room or container is made as tight as possible. 

 The temperature should be 70 deg. Fahr. or above, as poor and unsatis- 

 factory results are sure to follow even excessive doses at a lower tem- 

 perature. In a tight compartment five pounds to every thousand cubic 

 feet gives excellent results in killing weevils. If the compartments 

 cannot be made tight, increase the amount of carbon bisulfid. 



For Root Pests.— In the field this liquid is used to kill root pests as 

 woolly aphis, black peach aphis, phylloxera, grubs, maggots, etc., but 

 is practical only in sandy or porous soils. For a small plant a single 

 hole is made near the base and a teaspoonful of the lirpiid poured in 

 and the hole covered to prevent outside evaporation. For larger plants 

 several or many holes should be made, deep enough to allow the liquid 

 to evaporate around the infested roots. A syringe-like instrument is 

 sometimes used to inject the liquid around the roots. 



For Borers. — Injections of carbon bisulfid into the burrows of wood 

 borers and stopping the entrance of the burrows will kill all the insects 

 reached by the gas. 



For Ants and Wasp Nests. — A small amount of this liquid poured 

 into underground nests of ants, wasps, etc., will suffice to destroy the 

 inhabitants very quickly. 



TOBACCO FUMES. 



For very tender house and greenhouse plants infested with plant 

 lice, thrips, etc., it is sometimes advisable to fumigate them with slowly 

 burning tobacco, but even in such cases hydrocyanic acid gas is replacing 

 the more uncertain tobacco fumes. 



HYDROCYANIC ACID GAS. 



Hydrocyanic acid gas is generated by the addition of diluted sul- 

 phuric acid to sodium or potassium cyanide. The generation is made 

 in an earthenware jar, the gas being confined in a fumigation house 

 or, if the work is being done in the orchard, in a teat thrown over the 

 tree. For many years the methods of fumigation depended entirely 

 upon each fumigator, there being no uniform or common procedure. 

 The results of this early work so clearly showed the need of systematism 

 that the United States Department of Agriculture set experts to work 

 out a reliable and uniform system of procedure. Dr. A. W. Morrill 

 inaugurated our present system of marked tents and a system of dosage, 

 which is known as "The INIorrill System." This work w^as done in 

 Florida. Later Mr. R. S. Woglum began operations in California and 

 greatly perfected this system so as to make it at once practical and 

 available to all the orchardists. 



