542 ON THE DESTRUCTION OF NOXIOUS INSECTS. 



collection. Finally, a most important advantage of tliis powder is that 

 it is innocuous to man, and can be absorbed by the buman subject 

 without the slightest danger to his health. Some physicians of celebrity 

 even assert that the powder can be advantageously sprinkled upon sores 

 or open wounds that diffuse an unpleasant odour. 



Mode of Applying the Powder. — In using the powder it must be ap- 

 plied carefully and in sufficient quantity, otherwise the result will be 

 unsatisfactory, especially if used against some of the hardy or very 

 resisting species of insects. Occasionally the powder, by being exposed 

 to the air or moisture, will have lost its destructive properties, so as to 

 render the result doubtful and wholly inefficient ; at others the result 

 has been unsatisfactory because the most favourable moment for the 

 operation has been overlooked. A rainy or wet day, for instance, always 

 lessens the destructive efficacy, because the powder, containing a very 

 volatile essential oil, renders the conservation of this principle extremely 

 difficult. 



Of all the methods for applying the powder to plants attacked by 

 insects, including the vine, the bellows will best accomplish the object. 

 As there is only a small quantity of powder thrown at once, the loss will 

 be very small, whilst in any other way a good deal of it will fall upon 

 the ground. The powder should be directly applied to the parts operated 

 on, and with care and precaution it may be made to penetrate into the 

 most inaccessible parts of a plant. If, for instance, a plant has been 

 attacked by plant lice, which are often hidden or masked by thick 

 foliage, it will become necessary to turn aside this foliage, so as to have 

 the insects exposed and the powder directly brought into contact with them. 



In all cases these operations should take place on a warm day, the 

 morning being always preferable. A slight moisture arising from the 

 morning dew will make the powder more easily adhere to the spots 

 where it is applied, and maintain its properties long enough to cause the 

 death of the insects. The insufflation should be renewed several times, 

 according to the nature and number of insects to be destroyed. The first 

 operation generally stupifies them, while at the second or third applica- 

 tion they lose their strength, fall to the ground and die sooner or later. 



In order to prevent the ravages of the wheat midge, the powder is 

 mixed with the grain to be sown, in the proportion of about two 

 ounces to two or three bushels, which will save a year's crop. 



For insects in dwellings the insufflation may be performed by bellows 

 of a smaller size than those used in agriculture and. horticulture. 

 Proper care should be taken to make the powder penetrate to the recesses 

 where the insects lodge. Household furniture ought to be scrupulously 

 searched, and bedsteads and sofas sprinkled in the evening. By continu- 

 ing this for several days, the premises will be thoroughly rid of insects. 



For the preservation of furs, woollen garments or patterns, it is 

 necessary, at the approach of spring, to sprinkle the articles abundantly 

 with the powder, the object in contemplation being not the destruction 

 of the insects, but the preventing their reappearance. 



