QUASSIA. 375 



be disinfected at the same time. Gillette has studied the effects of 

 powdered tobacco [? snuff] in this particular instance. It is now re- 

 garded just as it is bought as an infallible specific for the destruction 

 of the underground form of this louse. Powdered tobacco mixed with 

 earth is frequently used in nurseries and also for other crops. 



Phylloxera vastatrix, Planch, (phylloxera of the vine). — Mouillefert 

 found tobacco juice destroyed this aphis. 



Tmgis Piri, Fl. (tiger of the pear-tree). — Sajo advises 2 lb. of 

 tobacco juice containing 14-5 per cent of nicotine in 100 gallons of 

 water as a means of radically destroying the tiger, but care must be 

 taken to direct the jet on the lower surface of the leaves. 



Pulvinaria vitis, L. {Coccus vitis), (vine scale). — Targioni-Tozzetti 

 advises to destroy the mobile larvae of this cochineal by spraying with 

 tobacco powder or using powders with a nicotine basis. Mohr praises 

 the effects of the following mixture deadly to cochineals in general : 

 Add 25 lb. of soft soap, 20 lb. of ammonia, 20 lb. of oleic acid per 100 

 gallons of tobacco juice. Guozdenovic records the good effects of a 

 mixture of 1-5 per cent of tol)acco juice and 0-5 per cent of soft soap 

 against the Dactylopiiis ritis (white cochineal of the vine). 



Thrips hamorrhoidalls, Bche. (black thrips of greenhouses or 

 black fly of the gardener). — It infests plants in greenhouses, and under 

 cloche, such as azaleas, camelias, fuschia, and causes them to fade. 

 It may be overcome, according to Decaisne, by powdered tobacco and 

 fumigations. Noel advises to soak the residues from the manufacture 

 of tobacco in a solution of 2 lb. of nitrate of potash in a gallon of water 

 and then dry it and burn it in the hothouse. 



Liviithrips Tritici (thrips which ravage onions). — It may be 

 destroyed, according to Webster and Eathay, by a decoction of tobacco. 



[Animal and plant lice are effectively treated by tobacco juice.] 



Phyllocoptus Schlechtendali, Nal. (browning of the leaves of the 

 pear-tree). ^This acarus may be destroyed, according to Sirodot, by 

 tobacco juice marking 1-5° B. and sprayed on all the parts of the tree. 



Greenhouse acari do not stand fumigation (Decaisne) nor spraying 

 with the mixture of ammonia, tobacco juice, soap, and oleic acid to be 

 used against vine scale (Mohr). 



Tetranychus telarms (red spider). — Eathay kills this tree louse 

 with tobacco juice. 



Tetranychus althaea (Tetranychus which causes the rusting of 

 the leaves of the hop), (Kupferbrand). It is overcome, according to Voss, 

 by preventive treatment. In the autumn the soil is dusted with 

 powdered tobacco [? snuff]. Spraying with tobacco juice has 

 little effect on adult tetranychus living on the plant (Sorauer). 

 Voss' method is preventive. It kills the tetranychus which hibernate 

 under the leaves on the hop fields and prevents the return of the 



144. Quassia Amara [true.] — Quassia is derived from a Guiana 

 tree, the quassia tree [Quassia Amara]. The quassia of the shops is the 

 wood of Picrena Excelsa, belonging to the family of Simarubiacecs. 

 The wood and the roots are sold as chips or lumps (Lignum QuassiccE). 

 To extract the quassia the chips are macerated for twenty-four hours 

 in water. Insecticides with a quassia basis are prepared thus : (1) Boil 



