ECONOMIC ZOOLOfiV — ENTOMOLOGY. 661 



appear to lie <If'<'(iiii|'<is('(l, (nniiint,' idiiiiMiimds ((nilaiiiiiiL; niiicli less siilplitir than 

 thf tctnisiiljtliid (CaS,). 



A (•((iicciit rated solution was dilntcd to 50 j^al., nsinj; H j^al. of water for 1 

 gal. of concent i-ate, and 10 Ihs. of lime then added. "The auiounl of snlphiil 

 sulphur was decreased, while thiosulpluite was increased with formation of 

 free sulphur. The lii^ln'r sulphids of calcium were decomposed, forming com- 

 pounds containing less suli)hur. The changes thus caused may Ix' so great as 

 to seriously decrease the insecticidal jiower of the mixture. 



" When nearly pure lime is usckI, the sediment c<msists largely of calcium 

 sulphite ((^aSOa), free sulphur, hydroxid, and carhonate of lime, and can l)e 

 added to fresh amounts of sul])hur and lime in making additional wash. This 

 should not be done when the lime used contains magnesium compounds. 



" Magnesium oxid does not form sulphids when boiled wtih su]])hur. Some 

 limited action takes place which results in producing hydrogen-sulphid gas. 

 When magnesium oxid is present in lime, it tends to decompose and decrease 

 the amount of suliihids of calcium found. Hydrogen suli)hid gas thus produced 

 is jtoisonoiis and may affect unfavorably the person who handles the mixture 

 during boiling. 



" Sevei'al samples of each of four different brands of solutions were examined. 

 One brand contained varying amounts of sediment, one sample nearly 20 per 

 cent. The percentage of soluble sulphids was found to vary from 10..5 to 25.0; 

 in most cases the percentage was between 23 and 24. The suli)hid compounds 

 present were tetrasulphid (OaSi) and pentasulphid (CaSr,), the i)roportions 

 varying somewliat; on an average, tli<! two compounds were present in approxi- 

 mately efjual proi)ortions. 



"One sample of a dry powder was examined, the result showing that at the 

 price charged th<> cost is higher than in case of the commercial solutions." 



Concentrated lime-sulphur mixtures, P. J. Parrott (New York Hlalr HI a. 

 Bill. 320, pp. Jfl0-/f38, fig. 1). — Tests of these mixtures are reported and dis- 

 cussed. 



"Field experiments to test the value of the sediniont of a commercial lime- 

 sulphur mixture in controlling the San .Tose scale demonstrated that the in- 

 soluble portion ]>ossesses very weak, if any, insecticidal pi'operties on this pest. 

 The sulphur sprays derive their chief insecticidal value from the soluble lime- 

 sulphur compounds. The addition of the sediment of a commercial or home- 

 made lime-sulphur wash as extra material has apparently no detrimental in- 

 fluence on the effectiveness of the clear solution. The strength of the diluted 

 preparation should be based on the clear solution. 



"On the basis of reasonable efficiency and cost, the strengtlis of effective mix- 

 tures for the San .Tose scale, using a lime-sulphur solution testing '.i?>° R., range 

 from 1 gal. of the concentrate diluted with S gal. of water to 1 gal. of the 

 solution diluted witla 11 gal. of water. In orchards where tlie scale is not 

 thoi'onghly controlled, tlie stronger mixtures are recommended. For spraying 

 for the blistei'-mite, a dilution of 1 gal. of the concentrate to 11 gal. of water 

 makes an effective spray. 



" Present evidence indicates that the common spraying arsenicals do not mate- 

 rially affect the value of lime-sulphur mixtures. In si)raying for the scale or 

 blister-mite, an arsenical in the usual amount for orchard treatment may ap- 

 pai'ently be safely adde<l to a diluted sulphur solution for the purpose of con- 

 trolling the bnd-nioth and casebearers, which are now very destructive in many 

 apple orchards. 



"The second year's experiments with the home-made concentrated lime-sul- 

 phur wash gave satisfactory results on the scale and blister-mite. The different 

 preparations showed some variation in the density of the solution and in the 



