370 INSECTS AFFECTING VEGETATION 



at from 3^> cents to 4 cents a pound, making the mixture cost, as ap- 

 plied to the trees, from 7 cents to 8 cents a gallon. 



Soap Washes. The most effective soap wash is made with 

 whale-oil soap, one pound to from four to six gallons of water. The 

 term whale-oil soap is merely a trade name for fish-oil soap, made 

 with either potash or soda. The potash soaps, which are the best, 

 because even stronger solutions remain liquid when they cool, are 

 soft soaps. The soda soaps are hard. Of the two, the potash soaps 

 are considered the best to use on vegetation, as well as being more 

 convenient. Both kinds should always be dissolved in hot water. 



When bought at retail prices, these soaps cost from 15 to 20 

 cents per pound, according to the locality, but if obtained in large 

 quantities, can be got at from 3 to 5 cents per pound. Fifty-pound 

 kegs are supplied at 5 cents per pound. Two well-known brands of 

 potash soft soaps which have been much used in Canada, and have 

 given good satisfaction, are those made by W. H. Owen, of Port 

 Clinton, Ohio, and by Good & Co., of Philadelphia, Pa. If thought 

 desirable, these soaps can be made at home ; but it is very unpleasant 

 and dirty work, and it is, besides, doubtful whether such good or 

 cheap results can be secured as by buying from firms which make a 

 special business of manufacturing soaps with only the required 

 amount of moisture and the proper grade and amount of potash. It 

 has been found in experiments carried on at Washington that what 

 is required for spraying purposes is a caustic potash and fish-oil soap, 

 made with a fairly good quality of fish-oil, and from which water 

 has been eliminated by boiling, so that it does not exceed 25 or 30 

 per cent of the weight of the soap. Soaps made with caustic soda 

 instead of caustic potash are unsuitable for spraying purposes. Dr. 

 J. B. Smith (New Jersey Experiment Station), in his circular No. 5, 

 "Whale Oil Soap and Its Uses," says that whale-oil, or fish-oil, soap 

 is one of the most reliable materials for use against plant-lice, and 

 generally against sucking insects which can be killed by contact in- 

 secticides. It kills by clogging the spiracles, or breathing pores, of 

 the insects, and also to some extent by its corrosive action. The ad- 

 vantages of fish-oil over ordinary laundry soap lie in the greater pen- 

 etrating power, in the fact that it remains liquid when cold, at much 

 greater strengths, and that fish-oil itself seems to be more fatal to 

 insect life than other animal fats. A good soap can be made as 

 follows : 



Concentrated potash lye ................. 3% pounds. 



Water ................................ 7% gallons. 



Fish-oil .............................. 1 gallon. 



Dissolve the lye in water, boil, and to the boiling solution add 

 the fish-oil; continue to boil for two hours, and then allow to cool. 

 Any grade of fish-oil will answer. Whale-oil soap may be applied 

 in the strength of one pound in four gallons of water for brown or 

 black plant-lice, and one pound in six gallons for green plant-lice ; 

 warm water should always be used when dissolving it. ^ Soaps of all 

 kinds are very useful in adding adhesiveness to liquid mixtures when 

 it is necessary to apply these to such vegetation as cabbages, turnips, 



