99 



on tender foliage. Rose-leaf insecticide, an extract of tobacco, one 

 part to from 25 to 40 parts of water, is the most satisfactor}' spra}^ we 

 have used against these aphides. It is, however, most disagreealile to 

 apply and rather too expensive for extensive use. Undoubtedly 

 tobacco water made by boiling 1 pound of refuse tobacco in 1 gallon 

 of water, with an equal amount of water added, will prove to be a good 

 remedy, though we have been unable to give it a thorough trial. 



The most satisfactory method of destroying these aphides on young 

 trees is b}' fumigation. In 1899 we made several tests in fumigating 

 them with hydrocyanic acid gas and found that they could be readily 

 destroyed in ten or fifteen minutes. This spring we had a fumigator 

 of the Geneva type constructed, covering it with strong muslin, which 

 was thoroughly painted with thin glue, and it proved entirely satis- 

 factor3^ This frame contained exactl}^ 200 cubic feet. The aphides 

 were entirely destroyed by burning 2 ounces of tobacco leaves and 

 fuinigating for fifteen minutes; also with one-half a roll of "aphis 

 punk" for twenty minutes. A larger amount of the latter would 

 probably be as effectual in a shorter time. "Aphis punk" is simply 

 paper dipped in a tobacco extract, and is in a handy form to use, 

 though rather expensive. Nikoteen and Nicoticide, both concentrated 

 extracts of tobacco, were used very successfully by diluting with 

 water and evaporating in shallow pans over an alcohol lamp furnished 

 b}" the manufacturers. One and one-half cubic centimeters of Niko- 

 teen diluted to 15 cubic centimeters with water killed the aphides in 

 fifteen minutes, as did 4 cubic centimeters diluted to 15 cubic centi- 

 meters in eleven minutes. It requires about five minutes for the 

 Nikoteen to evaporate. Five cubic centimeters of the Nicoticide 

 diluted with 5 cubic centimeters water killed the aphides in ten and 

 twelve minutes. The Nicoticide "is a very strong solution con- 

 taining 40 per cent of nicotine" (quoted from a letter of manu- 

 facturers) ; it is a thinner and more volatile liquid than Nikoteen or 

 Rose Leaf, evaporating over the lamp in about three minutes, and 

 seems to be more rapid in its effect upon the aphides. We are 

 inclined to regard this as the most satisfactory method of fighting 

 these aphides upon j^oung orchards. Usually but a few trees are 

 infested here and there, and as the lice do not spread very much until 

 the trees become overcrowded, by fumigating these few trees the 

 injury can be almost entirely checked, as the fumigation destroys 

 practically every aphid, whereas the best spray can not reach a very 

 large percentage of those protected on the curled leaves. 



A plain box or bell tent made of heavy, tight-woven muslin (we 

 found a brand termed "Cast iron," in use by hot-air balloonists, very 

 satisfactory) and painted with glue woidd be fully as satisfactory for 

 use on small trees, and much cheaper. The materials for a tent should 

 not cost over $2, and the making is a simple matter. With a dozen 



