27 



It is suggested that a syndicate! slioukl be formed on the hnes of that 

 inaugnrated in 1911 [R.A.It., A, vii, 466] to deal in a co-operative 

 manner with locust invasions. 



]\k)Ki;Au (I .) ^' ViNi'T (!<:.). Les Pi6ges-Appats dans la Lutte centre 



la Cochylis. [Bait-traps in liie (amp.iigu against Clysia 

 amhii^iiclla.l.—AnH. Service des Epiphy/ies, Paris, vi (1918), 1919, 

 pp. 299 312, 2 plat(>s. [Received 12th Noveml:)er 1920. J 

 Recent experiments with bait-traps for Clysia amhigueUa in French 

 vineyards have only served to coufirm the authors' o])inion expressed 

 in 1913, that while they hav(^ undoubtedly some value in protecting 

 vines against this moth, they cannot b(> regarded as anything 

 more than a com]->lementary measure \R.AJi., A,-ii, 16J. The experi- 

 ments hen^ described have led to the conclusion that tlie liquid used in 

 a liait-trap must have some odour if it is to have any attraction for the 

 moths. The addition of a roof-shelter to the traps is not necessary. 

 The maxinuun uuml)er of moths is caught shortly after sunset, and there 

 is a gradual decrease after 10 p.m. The number of females caught is 

 on an average 65-1 per cent, of the total. Atmospheric conditions 

 have an important influence on the numbers captured. The traps 

 arc not luiiform in their captiues, and it is necessary to take various 

 factors into consideration in determining their value. The degree of 

 protection conferred upon vines by bait-traps is estimated, judging 

 by the authors' own experiments, at 37-8 per cent, reduction in the 

 number of larvae in the spring and 24-8 per cent, in the number of 

 infested grapes in the summer. This latter figure is practically the 

 same as that calculated in 1913, viz., 26 per cent. 



These observations exphiin, in a great measure, the contradictory 

 results that have been obtained by various experimenters, and 

 demonstrate tlK> necessity of detailing the technique employed in any 

 tests, the climatic conditions imder which they were carried out, and 

 also the method employed in calculating their efficacy. 



Fe\ lAUD (J.). Essais de Traitements Arsenicaux tardifs centre 



I'Eud^mis. |lLX])eriments in late Arsi'uical Treatments against 



Polvchrosis bolrana.] — Ann. Service des Epiphytics, Paris, vi, 



(1918) 1919, pp. 313-319. [Received 12tli November 1920.] 



Experiments in the control of Polychrosis hotrana indicate that 



arsenical applications made after blossoming, for the control of the 



first generation, cannot replace preventive treatments, which give the 



best results. These late applications, although almost useless against 



the first infestation of larvae, exercise considerable control against the 



second generation, which damages the vines towards the end of July 



and beginning of August. Their elficacy against the second generation 



is, however, very inferior to that of a preventive nicotine treatment 



made towards the end of July. It is pointed out that the measures 



adopted in France differ essentially from those made against P. viteana 



in America, where the biology and conditions are both different. 



In view of the legislation restricting the use of arsenicals in France 

 ^R.A.E., A, V, 47, etc. I it is suggested that an arsenical or nicotine 

 jireventive treatment should be given before the blossoming to destroy 

 the eggs and larvae of the first generation, this being followed by a 

 l)reventive nicotine treatment against the eggs and larvae of the second 

 generation. A comi)lementary treatment of nicotine, pyridine or 

 ])yrethrum, in the form of a liquid pressure spray, might be given during 

 the blossoming period to destroy the larvae while infesting the flowers. 



