INSECTICIDES AND THEIR USES 35 



Sprinkled over the surface as a top dressing. In fields of potato 

 it should be applied between rows and covered by earth, by 

 drilling or other process, as there is a possibility of injury to 

 plants, and this method should be used experimentally at first. 

 The amount to use will vary according to the degree of infesta- 

 tion by white grubs and other conditions. It has been employed 

 at about the rate of 4 barrels to 100 square feet of ground on 

 a lawn with the result that the spring after application all 

 forms of vegetation, including weeds, came up, and only five 

 or six white grubs could be found. In Europe gas lime has 

 been used with some success in connection with other remedies 

 for wireworms at the rate of i>^ tons to the acre. 



The best time to apply the lime is in September, after the 

 crop is made. 



Caution.— There is always danger to plant life in the use 

 of gas lime, hence before employing it on growing crops on a 

 large scale it should first be used experimentally. 



Hellebore, or white hellebore (Verafrum album) is less dan- 

 gerous than the arsenicals, hence has some votaries for its use 

 on cabbage and other plants soon to be eaten. Its use is open 

 to the same objection as pyrethrum that it loses its insecticidal 

 properties by exposure to the air. It is also poisonous to 

 man and domestic animals. It is a specific against the slugs or 

 false-worms (none of which commonly affect vegetables), which 

 attack raspberry, currants and other bush fruits. As many truck- 

 growers raise bush fruits it might be added that it is used in 

 both dry and liquid form, but can be applied more thoroughly 

 as a spray, >4 ounce of powder to 2 gallons of water. Dr. 

 James Fletcher recommends its employment as a remedy for 

 certain kinds of cabbage pests, including "worms" and root- 

 maggots. On the latter it is applied at the rate of 2 ounces of 

 powder to the gallon of water, and applied with a force-pump 

 about the infested roots. 



