44 INSECTICIDES AND SPRAYING 



Poisoned Grain. Corn may be soaked in a strychnine solution, 

 rendering it poisonous to crows, squirrels or gophers, and may be 

 scattered about in fields where crows are working. The method of 

 making and using this solution is as follows: 



One ounce of sulfate of strychnia is dissolved in two quarts of 

 boiling water. This is sufficient to treat a bushel of grain, which 

 should soak over night. The poison should be prepared and mixed 

 with the grain in a metal container and the latter thoroughly 

 cleansed after the operation. Wheat is used when mice or gophers 

 or prairie dogs are to be poisoned. Crushed or rolled oats form a 

 good basis for a poison bait. Seed corn may also be safely treated 

 with this preparation. The United States Department of Agricul- 

 ture (Farmers' Bulletin 670) recommends for field mice the adding 

 of two tablespoonfuls of laundry starch in one-half pint of cold 

 water to either of the above poisons, pouring the starch into the 

 solution and boiling for a few minutes, then pouring it over the 

 grain. Care should be taken to prevent stock or poultry having 

 access to poison baits. 



Tarred corn can be prepared in such a way as to enable it to 

 pass easily through the planter (see under Crow, page 405). This 

 treatment also renders it distasteful to wire worms, squirrels and 

 gophers which sometimes attack the planted seed. 



9. Arsenite of Soda. One-fifth ounce of arsenite of soda, one- 

 half pint of New Orleans molasses and one gallon of water sprayed 

 on young cabbage, cauliflower, onion plants and radishes attract 

 and poison the adult flies which produce the destructive maggots. 

 To be effective they must be applied early, before egg laying begins. 



Bait for Sow-bugs. Paris green or arsenic on slices of potato 

 is claimed to be a successful bait for sow-bugs (not insects) in 

 greenhouses. We have successfully used a mixture of Paris green 

 and sugar. The Florists 9 Review advises for sow-bugs, two 

 parts rye flour, two parts sugar, one part Paris green, kept dry and 

 frequently renewed. 



Insecticides for Sucking Insects. Contact insecticides are in- 

 tended for such insects as do not eat the surface of plant, but suck 

 the sap from below it. Entomologists formerly believed that soap, 

 oil, or oil mixtures killed by stopping the spiracles and thus 

 "smothering" the insect. This theory appears to be, in part at 

 least, disproved, since insects can live a long time without access 

 to oxygen. It is now thought that their death is due to volatile 

 substances in oil or soap. 



