No. 4.] INJURIOUS INSECTS. 155 



placed in the insectary greenhouse, and, as they were found 

 to have a few plant lice and red spiders on them, they were 

 carefully protected till they multiplied and covered every 

 green twig and more or less of the surface of the leaves. A 

 pailful of kerosene emulsion was then prepared, and each 

 rose bush was inverted, dipped into it and held there about 

 a quarter of a minute, or long enough to allow the emulsion 

 to reach every insect on the bush. An examination of the 

 bushes two days later failed to reveal a single plant louse or 

 red spider, and none appeared on them during the remainder 

 of the season, thus proving that the work was not only 

 thorough but effectual. 



This method of killing the lice can only be applied to 

 small plants in pots ; but for trees and shrubs it becomes 

 necessary to spray with kerosene emulsion for the destruction 

 of plant lice. It must be remembered, however, that this is 

 a contact insecticide, and every individual must be drenched 

 with the emulsion to make it effectual. If a few of the lice 

 escape this drenching, so great are their powers of repro- 

 duction, as shown above, that they will soon increase to 

 such an extent that it will be necessary to spray the tree 

 again. 



To prepare kerosene emulsion, dissolve one-quarter of a 

 pound of common bar soap in two quarts of boiling water, 

 and, while still hot, add four quarts of kerosene oil and 

 churn it for about five minutes through a small hand force 

 pump with a small nozzle turned into the pail. When 

 properly done, the whole forms a creamy white mass, which 

 becomes jelly-like when cold. Care must be taken to have 

 the solution of soap hot when the kerosene is added to it 

 and the churning done, but it must not be near a fire. Be- 

 fore applying this emulsion to the plants, it should be diluted 

 with water in the proportion of one quart of the emulsion 

 to nine quarts of water, and then thoroughly mixed. The 

 above will make sixty quarts of the insecticide ready for 

 use. The emulsion will keep for a long time without injury, 

 and may be diluted when needed for use. I have often had 

 the feeling that when I have advised this plan and it has been 

 tried, and a few insects have escaped and multiplied so that 

 it would be necessary to go over the whole thing again, the 



