543 



Tfsin, which sokition is commercially obtainable in Germany, serve to 

 produce the sodium-resinol spray if diluted with water, and the lime- 

 resinol spray if diluted with a solution of calcium chloride. These 

 sprays have the same wetting power as soap solutions, and in the 

 presence of atmospheric carbonic acid they soon decompose and liberate 

 the resin. Decomposition may take place prior to use, and the resin 

 then appears in the liquid in the form of a flocculent, emulsion-like 

 precipitate. After the spray-fluid has evaporated, the resin remains, 

 adhering with such tenacity as to afford a certain degree of protection 

 for some considerable time. 



A number of experiments with the caterpillars of Pieris brassicae 

 are described in detail. It was found that the soluble resinol salts 

 have a three-fold action. They first increase the adhesive power of 

 water, thus enabling the surface of an insect's bod}^ to be wetted, and 

 they make penetration into the stigmata possible. They then clog 

 or seal the tracheae and their approaches by precipitating a thick 

 solution of resin. Thirdly they dissolve or emulsify substances 

 insoluble in water, such as carbon bisulphide ; this may increase their 

 activity. 



A review of the substances acting in a similar manner at once directs 

 attention to lime-sulphur, which in fact is the best spray for the San 

 Jose scale [Aspidiotus j)erniciosus\. Resinol can therefore prove 

 successful only if the above three actions are most marked in the 

 presence of the material it is desired to affect and if it can be produced 

 at a suitable cost. In most cases chemical remedial methods will be 

 permissible only if treatment acts on fungus and insect pests simul- 

 taneously, and resinol may prove specially adapted for this purpose. 

 The author's previous work with resinol was directed against fungi, 

 and it was in the course of those experiments that its insecticidal action 

 was first noticed. 



In an addendum dated June 1920 it is stated that caterpillars of the 

 first generation of Clysia {Conchylis) [ambiguella] are even more sus- 

 ceptible than those of Pieris. A sodium-resinol solution of 0*4-0"6 

 per cent, strength proves rapidly fatal. With the addition of carbon 

 bisulphide, solutions containing 0*1 per cent, or less of resinol proved 

 fatal. Tobacco extract also increases the effect. 



Potash soap being available, it was found that strengths of l"6-2 

 per cent, are fatal. In this case the penetration of the fluid seems 

 sufficient to cause dea,th ; the clogging of the stigmata does not seem 

 necessary. Soap, however, can be washed off after appHcation, whereas 

 resinol solutions are decomposed and remain adherent. 



Kleine (R.). Sind manche Phyllotreta- Arten wirklich Getreide- 

 schadlinge. [Are some species of Phyllotreta really Pests of 

 Grain.] — Zeitschr.f. angeiv. Entom., Berlin, vii, no. 1, September 

 1920, pp. 48-57, 4 figs.' 



Several observers have recorded the infestation of grain by Phyllo- 

 ireta, the two species mentioned being P. vittula, Redt., and P. atra, 

 F., but their status as pests has remained doubtful. 



Observations on P. vittula in a field of grain in Pomerania, showed 

 that rye suffered most, barley less and oats least, even when the 

 plants were intermingled. The surface of the ground was uneven., and 



