58 INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Since the publication of the government circulars on this insect 

 there has been a great improvement of commercial or proprietary 

 miscible oils and emulsions, so that at the present time if the grower 

 does not desire to make his own distillate oil emulsion he is able to 

 select from three or four commercial products put out by reliable 

 companies, and which are uniform in quality and which can be easily 

 emulsified. These proprietary products are divided into two main 

 groups: those of a mechanical type of emulsion similar to the stock 

 home-made emulsions and running about 60 per cent oil, and those of 

 the miscible oil type running from 85 to 88 per cent oil, besides con- 

 taining a certain amount of phenols, which also have insecticidal 

 value, and which many people claim act as a deterrent for the thrips. 

 Those commercial preparations which run 60 per cent oil should be 

 diluted to get a 3 per cent emulsion at the rate of 10 gallons per 200 

 gallon tank, while those of the miscible oil type, analyzing 85 to 89 

 per cent hydro-carbon oils and including 1 to 3 per cent phenols, 

 should be used as advised by the companies making them. When 

 used against adults the usual dilution of this t.ype of oil sprays is 5 

 gallons per 200-gallon tank, combined with black leaf 40, 1-1,600, 

 and from 3 to 4 gallons with the nicotine when used against larva?. 



Many of the miscible oils are made from a more penetrating oil 

 than can be obtained by the average grower for making the home- 

 made distillate oil emulsions, and in cases of severe thrips infestation 

 will give better penetration, especially when used against adults 

 when the buds are only slightly open. 



The relative costs between home-made and proprietary insecticides, 

 where the labor is not taken into consideration, is in favor of the 

 home-made preparation. Home-made distillate oil emulsions run 

 from 55c to 65c per 200-gallon tank, besides the quantity of nicotine. 

 In the cheapest of the high-class commercial mixtures the cost runs 

 from 75c to $1.50 per 200-gallon tank besides the quantity of nicotine 

 used. One disadvantage home-made distillate oil emulsion has is that 

 if any is left over the next year it is practically worthless on account 

 of breaking down, whereas the commercial product can be kept 

 indefinitely. 



Oftentimes a saprophytic fungus, commonly knoAvn as one of the 

 blue molds, becomes very injurious in the pear buds following the 

 attack of the adult thrips, which have caused the buds to drip or 

 bleed. When this is present, a fungicide in the form of atomic or 

 milled sulphur, at the rate of 20 to 24 pounds per 200-gallon tank, can 

 be added to the Distillate Oil Emulsion-Tobacco, or Miscible Oil- 

 Tobacco mixture. The sulphur will prevent and stop the spread of 

 the blue mold, which often causes as much damage as the trips them- 

 selves. 



In spraying for the larva* or white thrips, a still greater combina- 

 tion can be used with advantage, as the time of application of this 

 treatment usually falls at the time when the first codlin-moth applica- 

 tion should be made on pears. For thrips larvas, codlin-moth and 

 pear scab use the above formula with the addition of 4 pounds of 

 arsenate of lead per 100 gallons of mixture. 



