81 



both in the green and brown variety on lettuces, and often destroys a 

 seed-crop. Pemphigus bnrsarius is a gall-forming pest of poplars. 

 Among root-aphids are A. myrmecaria, which attacks garden-plants, 

 and Forda troglodytes, which infests vegetables. 



The basis of the best spray for the control of these Aphids is a 

 solution of potash soap, 1 or \\ per cent, in water ; to this should be 

 added 1 per cent, of extract of tobacco, cresyl or lysol, or | per cent, 

 only in the case of very delicate plants. This preparation is rendered 

 much more effective by the addition of a decoction of 2 lb. of the leaves 

 and buds of peach, tomato or potato, in 2 gallons of water. A second 

 •spraying should be given after four or five days. For root-aphids, the 

 same mixture can be used to water the ground, thoroughly saturating 

 the area infested by the insects. Calcium carbide also gives good 

 results, using 2 lb. per square yard of ground. When scattered, this 

 should be dug in to a depth of 10 inches. Cyanide of potassium and 

 carbon bisulphide are also efficacious, but their use is somewhat difficult 

 and costly. 



These Aphids have many enemies in Colombia, the chief being 

 Coccinellids, Hemerobiids and a small species of ant. The principal 

 enemy of the root-aphids is a fungus, which is unfortunately rare, 

 being apparently unable to resist the excessive heat and prolonged 

 droughts. 



La Polilla en las Papas. [The Potato Moth.] — Revista Agricola, Bogota, 

 ii, no. 6, June 1916, pp. 353-355. [From Revista de las Asoci- 

 acion Rural del Uruguai/, xlv, no. 2, February 1916.] [Received 

 8th December 1916.] 



Phthorimaea operculella {solanella) attacks both the growing potato- 

 plant and the stored tubers. The climate of Colombia favours the 

 development of this moth throughout the year. If potatoes are 

 iafested at the time of gathering, they should be treated for ten minutes 

 in a bath of 2 per cent, sulphate of copper and should be stored in a 

 room well disinfected with sulphur. If the moths appear in the store- 

 room, 1|- to 2 ozs. sulphur to each cubic yard should be burnt and the 

 room sealed for 48 hours. This should be done once a fortnight, in 

 order to kill the moths which have emerged from the larvae present 

 in the tubers at the previous disinfection. Those varieties in which 

 the tubers grow very near the surface, should be sowed thinly, so that 

 the plants may be well tilled and the tubers will not be exposed to 

 attack. Shoots which have been attacked by the larvae should be 

 cut off and burnt. 



Fungicidas e Insecticidas mas usados para combatir las Enfermedades 

 de las Plantas. [Fungicides and Insecticides most commonly used 

 to combat the Diseases of Plants.]' — Revista Agricola, Bogota, ii, 

 no. 6, June 1916, pp. 341-348. [Received 8th December 1916.] 



The formulae contained in this article have been tested by the 

 Estacion de Patologia Vegetal, and used very successfully on a large 

 scale. 



Petroleum emulsion. Formula I : — Petroleum, 1| pints ; soap, 

 2 oz. ; water, 2 gals. The soap is dissolved in one pint of water and 

 the petroleum is added gradually, stirring all the time until an 



(C346) c 



