392 INSECTS AFFECTING VEGETATION 



waterings to be repeated for two or three days. The larvae go to 

 deeper and deeper levels and eventually die. 



Potash Fertilizers. For white grubs, wireworms, cutworms, 

 corn root-worms, and like insects, on the authority of Prof. J. B. 

 Smith, either kainit or the muriate of potash the former being 

 the better are broadcasted in fertilizing quantities, preferably be- 

 fore or during a rain, so that the material is dissolved and carried 

 into the soil at once. These not onlv act to destroy the Iarva3 in the 

 soil, but are deterrents, and truck lands constantly fertilized with 

 these substances are noticeably free from attacks of insects. This, 

 in a measure, results from the increased vigor and greater resisting 

 power of the plants, which of itself more than compensates for the 

 cost of the treatment. 



For the root-aphis of peach and apple, work the fertilizer into 

 the general surface of the soil about the trees, or put it into a trench 

 about the tree 2 feet distant from the trunk. For cabbage and 

 onion maggots, apply in little trenches along the rows at the rate 

 of 300 to 500 pounds to the acre, and cover with soil. These ferti- 

 lizers (and the nitrate of soda is nearly as good) are also destructive 

 to the various insects which enter the soil for hibernation or to 

 undergo transformation. 



Bisulphid of Carbon. This is the great French remedy for the 

 phylloxera, 150,000 acres being now subjected to treatment with it, 

 and applies equally well to all other root-inhabiting aphides. The 

 treatment is made at any season except the period of ripening of the 

 fruit and consists in making holes about the vines 1 foot to 16 inches 

 deep and pouring into each about one-half ounce of the bisulphid, 

 and closing the holes with the foot. The injections are made about 

 l 1 /^ feet apart, and not closer to the vines than 1 foot. It is better 

 to use a large number of small doses than a few large ones. Hand 

 injectors and injecting plows are employed in France to put the 

 bisulphid into the soil about the vines, but a short stick or iron bar 

 may take the place of these injectors for limited tracts. 



The use of bisulphid of carbon for the woolly aphis is the samo 

 as for the grape root-aphis or phylloxera. It should be applied in 

 two or three holes about the tree to a depth of from 6 to 12 inches 

 and not closer than l 1 /^ feet to the tree. An ounce of the chemical 

 should be introduced into each hole, which should be immediately 

 closed. 



For root-maggots a teaspoonful is poured into a hole near the 

 base of the plant, being covered as above. For ant nests an ounce 

 of the substance is poured into each of several holes made in the 

 space occupied by the ants, the openings being then closed; or the 

 action is made more rapid by covering with a wet blanket for ten 

 minutes and then exploding the vapor at the mouth of the holes 

 with a torch, the explosion driving the fumes more thoroughly 

 through the soil. 



Submersion. This very successful means against the phyll- 

 oxera is now practiced over some 75,000 acres of vineyards in Franco 

 which were once clestroyecl by the grape root-aphis, and the produc- 



