HELLEBORE AND KEROSENE AS INSECTICIDES. 43 



The common poke-weed, Veratmm viride, which grows so commonly 

 in wet meadows, should have similar insecticidal properties, but we are 

 not aware that it has been tested for the purpose. Whenever the pre- 

 pared powder cannot be conveniently procured, this might be resorted 

 to, as a substitute, by making a decoction of it with boiling water. 



The following are references to some of the writings which have 

 treated of the insecticidal properties of hellebore : 



Fitch's Twelftli Report; in Trans. N. T. St. Agricul. Soc. for 1867, xxvii, 1868, 

 pp.911, 919, 928. 930. 



Ganad. Entomol., ii, 1869, pp. 13-15 (efifects on currant- worms). 



Fourth Rep. Ins. Mo., 1872, p. 14 (useless against Colorado potato beetle). 



Ninth Rep. Ins. Mo., 1877, pp. 13-lG (method of use, etc.). 



Ormerod's Rep. laj. Ins. for 1881, pp. 7 , 43 (destroys cabbage butterfly larva and 

 pine saw-fly). 



5. Kerosene as an Insecticide. 

 While most of the oils are deadly to insects, kerosene seems particu- 

 larly so, perhaps from the rapidity with which it spreads over the sur- 

 face of the insect to which it is applied, at once reaching and closing 

 the breathing pores and producing, through suffocation, speedy death. 

 It is one of the cheapest of the insecticides and is among the most 

 efficient, wherever it can be used without injury to vegetation. In 

 many cases foliage has been injured by its application, and there 

 seems to be justly a prejudice against its general employment, as the 

 statements of experiments made with it are rather contradictory. 

 While it is generally thought necessary to use it only when greatly 

 diluted with water, yet Prof. Comstock reports that he has sprayed it 

 undiluted upon orange leaves and ivy to destroy scale insects, and 

 upon Cratcegus to destroy the wooly^apple louse {ScJiizoneura lan- 

 igera) without the least injury to the foliage. The following testi- 

 mony is borne to its value in the destruction of a class of insects which 

 are among our most persistent and pernicious pests : " After the fail- 

 ure of many attempts to eradicate this insect [a scale insect infesting 

 a number of imported varieties of orange, lemon, lime, etc., in the 

 grounds of the Department of Agriculture at Washington] the col- 

 lection may now be said to be entirely rid of it. This has been ef- 

 fected by the persistent use of a small quantity of coal oil [kerosene] 

 applied in water. About one gill of astral oil in five gallons of water 

 applied to the plants through a syringe on alternate days for several 

 months has destroyed the insects without injury to the plants ; weaker 

 solutions seemed ineffective, and when the oil was increased to an ap- 

 preciable degree, the young leaves and tender shoots of the oranges 

 were injured, '"'•'' 



*Ann. Rep. Commis. Agricul. for 1878, pp. 205-6. 



