Insect Killers. 341 



young lice are hatched and most easily destroyed. In the case of 

 bark lice it is well, also, during winter or earl}' spring, to scrape 

 the limbs, and thus remove and destroy a large proportion of the 

 scales under which the eggs are lodged, or the same purpose may 

 be effected by the use of a stiff scrubbing brush, dipped in strong 

 lye, or a solution of washing soda. 



Applications to destroy insects devouring the leaves may be 

 poisonous or non-poisonous. Among the latter hot water has 

 proved efficient, in maoy instances, and, since it is always avail- 

 able, it should, in the absence of more certain remedies, be 

 promptly used. The leaves of most plants and trees will bear the 

 free application of scalding water without injury, and when 

 showered on the larvae of insects it causes them to fall promptly 

 to the .ground, writhing with discomfort. Strong decoctions of 

 Quassia, May apple root and smart weed have also been found 

 serviceable; pepper in powder dusted on the foliage has also been 

 recommended. 



Of the poisonous compounds, Paris green, which is a compound 

 of arsenic and copper, in the proportion of — parts of the former 

 with — parts of the latter, is without doubt, the most generally 

 useful. It differs from most arsenical compounds in that it is 

 insoluble, and, hence, less likely to injure the plants to which it is 

 applied, when properly diluted. If used in a more concentrated 

 form it will, however, sometimes disfigure and scorch the foliage. 

 I have seen this effect produced on potato vines when the appli- 

 cation has been much stronger than necessary. The insolubility 

 of this poison seems to adapt it specially to act as a poison to 

 insects feeding on foliage. There are two points, mainly, which 

 have militated against universal concurrence in the efficacy of 

 Paris green. One is the fact that it is often largely adulterated. 

 There is so much competition now in business, and such an eager- 

 ness among the public for cheap goods, that the temptation to 

 pander to this feeding is very strong, especially since there is 

 money in it, and, hence, manufacturers are usually obliged to 

 make two or three grades in (juality in order to meet the demands 

 of their customers. The higher grades are usually pure, while 

 those lower in price are adulterated, containing, indeed, so much 



