52 



The Colorado Potato Beetle. 



This formidable pest of the potato-grower is now far too well known to require any 

 description. The accompanying wood-cut (Fig. 6) illustrates the insect in all its stages : 



Fig. 6. 



a the eggs ; b the orange coloured larva or grub at different periods of growth ; c the 

 chrysalis or pupa ; d the perfect beetle ; e one wing cover enlarged ; f a leg magnified. 



Though this destructive pest is now widespread over all the eastern half of this conti- 

 nent, wherever potatoes can be grown, and appears in infinite numbers everywhere, it can 

 yet be kept in check without much trouble or expense. As almost everybody knows, Paris 

 green is a perfect remedy for it, and by its timely use almost the whole of the crop can 

 be saved. The main point is to apply the poison carefully and promptly as soon as the 

 first brood of the insect appears in the spring ; by so doing the chances of a second attack 

 are very much diminished, but careful watch must be kept throughout the season and 

 the poison applied whenever any of the insects appear. If all the farmers throughout 

 the country would unite in using this remedy, we should in a few years so nearly exter- 

 minate the insect as to have little trouble from it. The most satisfactory mode of using 

 the poison, if the Paris green is pure, is to mix one teaspoonful in a pailful of water and 

 carefully sprinkle the affected parts with it ; an ordinary watering-can will be found 

 most convenient. As, however, the poison is often adulterated, it maybe found necessary 

 to use two or even three spoonfuls instead of one ; by trying the smaller quantity first 

 and watching its effect, the proper proportion may be readily ascertained. In the case of 

 the fully developed beetles a poison of much greater strength is required than for the 

 more delicate grubs. 



An objection to the use of Paris green has often been raised on the ground that it 

 injures the potato tuber and renders it a dangerous article of food by the absorption of 

 arsenic. Very careful and exhaustive experiments have been made in order to ascertain 

 whether any of the poison gets into the tubers or the roots and stems of the plant, with 

 the result that in no instance could any trace of the arsenic be found. The foliage to 

 which it is applied is often damaged to some extent by the corrosive action of the poison, 

 especially when too strong a mixture is used, but none of it is actually taken into the 

 plant so as to be stored up in the tuber. Any of the arsenic that reaches the ground is 

 Bpeedilj neutralized by the oxide of iron in the soil. Of course, in using this or any 

 other virulent poison, care must be taken to keep it out of the reach of children, and to 

 avoid using it in a garden where children play, or in a field to which cattle have access. 

 In such exceptional cases the insect may be kept in check by the more laborious method 

 of hand-picking. 



