386 Fruit-growing in Arid Regions 



plants which are most sensitive to arsenical poisons. When sus- 

 pended in water, this poison is so finely divided that it settles 

 slowly, and consequently can be more evenly distributed than 

 most arsenical mixtures. Its third point of superiority is in its 

 adhesive qualities when applied to foliage. Applications made 

 to foliage in the latter part of May at the Colorado Agricultural 

 College could be seen upon the leaves the first of September. 

 The disadvantage of the poison is its not being quite so quick to 

 kill the insects that eat it as are the other arsenites, consequently 

 it is necessary to use it in stronger mixtures. 

 The formula recommended is as follows: 



Arsenate of lead 2 to 4 pounds 



Water 100 gallons 



A stomach poison as are all preparations which contain arsenic. 



White Hellebore. Hellebore, as obtained from drug stores, is 

 a light, yellowish brown powder. It is a vegetable stomach 

 poison and is obtained by pulverizing the roots of an European 

 plant, Veratrum album. It is not as poisonous as the arsenites, 

 and consequently it is not as effective in the destruction of most 

 insects, but it has its special uses. Slugs, which are the young 

 of saw-flies, are particularly susceptible to its effects. The poison- 

 ous property is an alkaloid, and it loses its virtue after being ex- 

 posed to the air for a few days. For this reason it cannot be 

 used where it is likely to remain long before being eaten, and it 

 must be kept in tight receptacles and must not be kept too long 

 before using. It is often useful for the destruction of insects 

 upon plants containing fruit which will soon be used for food. 



Dry applications are easily made upon low plants by making 

 a small cheesecloth sack, through which the dust may be sifted 

 lightly over the foliage. The best time to apply is in the evening. 



In the wet way use: 



White hellebore 1 ounce 



Water 3 gallons 



Apply as a spray in the evening. 



