96 INSECTICIDES, FUNGICIDES, AND WRI^D KILLERS. 



pieces the size of a uut and then laid in front of the Une of invasion 

 of the locusts at the distance of a yard and in several parallel i*ows. 



Agrotis segetum, W. V. (the common dart moth) ; Agmtis ex- 

 clarnationis (the heart and dart moth). — Coquillot recommends 

 bunches of lucerne, steeped in a 1 per cent solution of aisenic, or the 

 preparation already prescribed to destroy locusts. The preparation is 

 placed round the stocks of the vines ; the grub, seeking its shelter in 

 the morning on the vine, grazes the arsenic of the preparation and is 

 poisoned by contact, for this product kills the insects that touch it as 

 well as those that absorb it through the digestive channels. 



Kermes. — It is asserted that these parasites do not resist a 1 to 3 

 per cent solution of arsenic. 



Phylloxera vastatri.v, Planch, (phylloxera of the vine). — The effects 

 of arsenic on this insect were examined by Cornu, Mouillefert, and 

 Heckel. Arsenious acid was proposed like other substances at the 

 moment of the phylloxeric invasion. The insecticide properties of 

 this product being known, it was hoped to be able to destroy this 

 formidable insect by watering the soil round the stocks with a dilute 

 solution of this poison. The phylloxera infected vines, after having 

 been stripped within a radius of 10 inches round the root, were each 

 treated with 25 grammes of arsenic dissolved in 10 litres of water. 

 [Dissolve 2| lb. arsenic in 100 gallons water and give each vine 24 

 gallons.] The adult phylloxera were found dead, but the young ones 

 were quite robust. As soon as the diffusive action of the soil had 

 rendered the arsenic powerless, the phylloxera multiplied once more. 

 Other trials showed that this dose is quite insufficient to destroy the 

 phylloxera of the vine. Vines so infected placed in pots containing 

 4 litres of earth received 1'5 gramme (23 grains) of ar"senic in 100 

 grammes (3^ oz.) of water. This, though a considerable dose, did not 

 free the vine from its parasites. It corresponded to 375 grammes of 

 arsenic per cubic metre of soil, and is not withstood by the vine, 

 which can stand a \ per cent solution, but a J per cent affects it. 

 Arsenic has not therefore been judged capable of being taken into 

 account for the destruction of the phylloxera. 



Rodents (mice, rats, field mice, moles). — Arsenic is the poison most 

 often used to destroy rats. The success of the famous poison " Rough 

 on Rats " is due to the arsenic it contains. 



There are different methods of making these preparations : (1) 

 Boil wheat in water saturated with arsenic ; boiling must not be too 

 prolonged, as the grains must remain hard. Place some of the grains, 

 after wiping them, in each hole. To destroy the field mouse it is 

 better to operate in winter, when the animal is famished. (2) Mix 

 100 grammes of arsenic (34^ oz.) with 1 kilogramme of tallow (say 

 2| lb.), 4 grammes I (say i oz.) anise, and 10 grammes (say J oz.) lamp- 

 black. The paste is spread on very thin slices of toasted bread. (3) 

 Mix 4^ oz. flour with 1 oz. of arsenic and place a little of the powder 

 in a drain pipe, about 1,^ inch in diameter ; place this pipe near the mole 

 holes. This method keeps the poison beyond the reach of game and 

 dogs. These pipes can also be used for poisoned grain. (4) Cut a celery 

 root in two parts, make a cavity in each piece, and fill it with arsenic, 



