SCALE-INSECTS. 33 



stance better for destroying Coccids and their eggs 

 than kerosene in the form of milk or soap emulsion, 

 diluted with water for evergreens or for trees with 

 insects on the leaves as well as on the bark. Pro- 

 bably, for deciduous fruit-trees the kerosene-and-oil 

 mixture is the best. 



The great point in favour of this substance is that 

 it destroys the eggs; this, few if any of the others 

 will accomplish. 



10. Lime. Of no avail whatever. 



11. Lye. Concentrated lye is very frequently recommended. 



In the New Zealand Parliamentary Papers (Codlin 

 Moth Committee Report, 1885, page 7) several state- 

 ments will be found apparently most favourable to it; 

 yet in places we find admissions that " it cannot reach 

 all the eggs." In America generally, it has not been 

 found satisfactory : " inferior to kerosene in killing- 

 power, and far more injurious to trees when used in 

 solutions strong enough to be effective as insecticides." 

 It is quite possible that the action of lye on the 

 fungus accompanying the scale-insects (see Chap. III.) 

 may have led " practical " gardeners to imagine that 

 it cleaned their trees of scale. Comstock says, " I 

 saw most excellent results from the following mix- 

 ture : lib. concentrated lye, one pint gasoline or 

 benzine, half pint oil, five gallons water." Probably 

 the good results here were due, not to the lye, but 

 to the gasoline and oil. 



12. Pyrethrum. Useless against Coccids (Comstock). 



13. Salt. Useless (Comstock). 



14. Soap. Undoubtedly a valuable remedy, and perhaps, in 



some cases, as efficient as kerosene ; but it does not 

 destroy the eggs. A solution of fib. of soap to a 

 gallon of water, applied hot } was entirely successful 

 in California : three months after its application no 

 living scale-insect could be found (Comstock). The 

 time of the year is not stated. In another case the 

 solution was applied cold : " four days after no living 

 insect could be found ; " but, again, the time of the 

 year is not stated, and no mention is made of the 

 eggs. Still, a strong solution of soap may be said 



