444 



AN ECONOMIC ENTOMOLOGY. 



A modification, somewhat more easily prepared, is — 



Kerosene .... 

 Hard soap . . . 

 Pyrethrum powder 

 Water 



I gallon. 

 I pound. 

 I pound. 

 I gallon. 



Dissolve the soap in boiling water ; then add the pyrethrum, and 

 stir, while continuing to boil, five minutes ; then add the kerosene 

 and emulsify as before. 



This mixture has been found effective with dilutions of from 

 four hundred to five hundred parts of water, but I have never 

 been able to secure equally satisfactory results. Indeed, in my 

 experience the pyrethrum adds little to the effectiveness of the 

 emulsion. Yet I would not discourage experiments with the 

 mixture, which may work better in other hands. 



Kerosene has also been used against scale insects on fruit- 

 trees in winter by spraying the pure material and in about ten 

 minutes setting fire to it. The kerosene burns off completely, 

 taking with it scales, moss, and fungous growths generally. This 

 use of it can be made on calm days only, as even a slow current 

 of air is apt to blow the flame from one side, making the applica- 

 tion ineffective. 



Gasoline, a much lighter oil, is useful as a contact insecticide 

 in a limited number of cases. It can be apphed to textiles in- 

 fested with ' ' moths, " or to carpets infested with ' ' carpet-beetles. ' ' 

 It is very penetrating, kills everything it touches, and evaporates 

 rapidly without influencing unfavorably any but the poorest fab- 

 rics. The material is very inflammable, however, and this should 

 be kept constantly in mind when using it. 



Soaps of various descriptions are useful contact insecticides, 

 and act through the stigmata, or breathing pores, by clogging 

 them and choking the insect to death. It is essential, to obtain 

 a good effect from a soap mixture, that the application be ex- 

 tremely thorough, so that each insect receives a complete coat- 

 ing. There is a great variety of insecticide soaps on the mar- 

 ket, but they all act in much the same way. In any good soap 

 the suds are capable of being thinned out to an almost impercep- 

 tible film, as we find in making soap-bubbles, and this, forming 

 over the spiracles, resists the entrance of air. We cover the in- 



