INSECTICIDES 53 



it will remain sticky for some weeks. It may be used in the same 

 way to prevent the wingless female canker worms and other 

 wingless insects from ascending trees, or to prevent the ascent of 

 caterpillars on unaffected trees. 



Various proprietary insecticides are frequently offered for sale 

 with wonderful claims for their effect as repellants, but only in rare 

 cases are they of any value except for use as a dust as already sug- 

 gested. One of the most common fakes of this sort is that of the 

 itinerant tree-doctor who offers to bore a hole in a tree and plug 

 it with sulfur or other offensive compounds, which will effectively 

 prevent any insect or fungous depredations. A generous price 

 per tree is charged, which is the only " effect " of the treatment. 



Bordeaux mixture is not, generally speaking, an insecticide 

 but it does have a repelling action on some insects, notably the 

 flea-beetles which attack potatoes and tomatoes. It is the most 

 widely used fungicide and it or lime sulfur " summer strength " 

 will practically always be included in the spray applied for insects, 

 so it is well for all interested in spraying to be familiar with bor- 

 deaux. It is prepared by mixing a solution containing three to 

 five pounds copper sulphate (bluestone), with a mixture of four 

 to six pounds lime. These may be in from 5 to 25 gallons of water 

 and should be mixed by pouring both at the same time into a 

 third container, usually the spray tank or barrel. The total 

 liquid from the above amounts should be 50 gallons. 



Asphalt paint and even asphaltum are applied to trunks and 

 branches of trees to keep out borers. Heating is generally required 

 and the application is somewhat difficult but good results have 

 been obtained. 



4. Gases 



Carbon Bisulfid (or disulfid) is extensively used against insects 

 affecting stored goods and grains, and for root-feeding insects. It 

 is a clear, volatile liquid giving off fumes heavier than air. It may 

 be thrown directly onto grain without injury to it or placed in 

 shallow dishes. For grain in store in fairly tight rooms apply one 

 pound to every 100 bushels, distributing the bisulfid over the 

 surface or in pans containing not over one-half to 1 pound each. 

 Make the enclosure as tight as possible, covering the grain with 

 blankets or other tight cover, if necessary, and leave for twenty- 



