148 The Spraying of Plants. 



HELLEBORE ; WHITE HELLEBORE ; EUROPEAN HELLEBORE ; 

 VERATRUM ALBUM. The roots of this plant and also of 

 Veratrum viride, American hellebore, when ground into a pow- 

 der possess considerable insecticidal value. The powder is of a 

 light yellowish-brown color, and possesses an odor which is not 

 wholly disagreeable. The active principle of the root, known as 

 Jervine, is a very powerful alkaloid. It generally destroys 

 an insect by being eaten with the food, but it appears 

 probable that it also possesses a certain value when it merely 

 comes in contact with the insect's body. Hellebore is much 

 less poisonous than the arsenical compounds, and it also soon 

 loses its strength when exposed to the air. For these reasons it 

 should be preferred to the mineral poisons when the plants to be 

 treated are bearing products which are nearly ready for market, 

 as ripening currants, or heading cabbages. If properly applied, 

 it is very effective in destroying chewing insects, and more than 

 two applications are rarely necessary. Only the fresh powder 

 should be used. It may be applied either in dry form or when 

 mixed with water. When used in the form of a dry powder, it 

 is generally applied pure, but may be successfully diluted with 

 once or twice its bulk of plaster, lime, or flour, the last causing 

 it to adhere more firmly to the foliage. In cases where the 

 insect does not yield readily to treatment, applications of the 

 pure powder may be advisable. The powder should be sifted 

 uniformly upon the foliage. 



When used in water the following formula may be success- 

 fully employed : 



Hellebore (fresh) 1 ounce. 



Water 3 gallons. 



Some recommend the addition of an ounce of glue to the 

 above mixture, or a small amount of flour, in order to render it 

 more adhesive ; yet for general practice such additions are 

 scarcely necessary. The use of one ounce of powdered soapstone 

 with the mixture of hellebore and water has also been recom- 

 mended as possessing especial value. The cost of good hellebore 

 varies from twelve to twenty-five cents per pound. 



HOT WATER. See WATER. 



HYDROCYANIC ACID GAS ; HCN. D. W. Coquillet was 

 the first to suggest and use this gas for the destruction of scale 



