PREVENTION AND DESTRUCTION OF INSECT PESTS. 493 



egress of the little active six-legged larval scales from beneath the 

 parent scale, and also to burn away certain of the soft scales. They 

 form by far the most successful scale -wash we have. There are 

 many recipes, but the one here given is found to be the best : 

 Resin, 24 lb. ; caustic soda, 5 lb. ; fish-oil, 3 pints, or 4^ lb. soft- 

 soap to 100 gallons of water. Less soda is wanted if soap is used. 

 First crush the resin by pounding it up in a sac ; then put the 

 resin in the cooking vessel and add two-thirds of a gallon of water 

 to every lb. of resin. Boil the caustic soda and then add the oil, 

 well mixing ; while still warm (better kept boiling) add the resin, 

 and stir well until the resin has quite dissolved. The mixtiu-e, 

 which is at first creamy, becomes coffee -coloured and clear ; the 

 boiling should be kept up for ten minutes after this brown stage 

 is reached, then add warm water to bring the mixture up to about 

 25 gallons. The wash is then complete. When used, add three 

 times as much water as concentrated wash, and apjjly warm at 

 about 130° Fahr. with a fine sprayer. This can only be used as a 

 winter wash, as it bums the foliage. 



3. Paraffin washes. — Paraflfin-oil or kerosene forms an excellent 

 insecticide and insectifuge, especially if it is used with soft-soap in 

 the form of an emulsion, by which the paraffin is> evenly distributed 

 in the water. This wash is most useful for celery fly, marguerite 

 fly, mealy bug, and plant-lice, and, with the addition of tobacco, it is 

 excellent for destroying thrips. Paraffin emulsion is prepared by 

 mixing equal proportions of boiling soft-soap solution and paraffin 

 together, and thoroughly churning them until a thick creamy emul- 

 sion is formed. This emulsion can be kept and mixed with sixteen 

 to thirty times its bulk of warm water when required for use. An- 

 other method is to dissolve 1 quart of soft-soap in 2 quarts of 

 boiling soft water. Remove from the fire, and while still boiling 

 hot add one pint of paraffin oil, and immediately churn the mixture 

 with a small hand syringe for five minutes. For use dilute with 

 ten times its volume of water (Cousins). It is also used for scale. It 

 has little or no effect, however, upon hard scales, such as the tortoise 

 scales {Lewianium) or mussel scales {Mytilaspis); but on certain of 

 the woolly-scales, such as the camellia scale (Pulvinaria camelicola), 

 it has good effects, destroying the active six-legged larvae that wander 

 amongst the wool. These latter scales are not permanently fixed, 

 whereas the tortoise scales, mussel scales, and oyster scales (Chion- 

 aspis) are, and thus we can only use this emulsion against them 

 at the time the larvse are crawling from beneath the scale, in the 



