300 



of zinc arsenite and lead arsenate were made. As previously observed, 

 milk of lime kills the eggs of Pohjchrosis. Death appears to be due 

 to dehydration or to tension, as the embryos continue to develop while 

 the lime is drying, but die when dessication is completed. This 

 hypothesis seems to be confirmed by the fact that the only eggs which 

 hatched out were those which were already in an advanced stage when 

 treated. As regards arsenicals, lead arsenate was again found to be 

 the most efficient. It is however one of the most dangerous, adding 

 the risk of saturnine poisoning to that of arsenical poisoning. Less 

 deadly, but equally efficient substitutes have been sought for, and 

 American entomologists have recommended ortho-arsenite of zinc. 

 In the laboratory tests here described, it was found that the effect of 

 lead arsenate and zinc arsenite is practically nil on the eggs of the vine- 

 moth. The former produced no result, though the latter killed a few 

 of the eggs. The remarkable aborting action of nicotine on the eggs [see 

 this Review, Ser. A, ii, p. 410] is due to an internal insecticidal action 

 on the developing caterpillars. The positive effect of nicotine and 

 the negative effect of lead arsenate may be explained by the more 

 rapid action of the former. Experiments on the caterpillars showed 

 that zinc arsenite from 2| to 3 per thousand is at least as efficacious 

 as lead arsenate prepared with 3 per thousand of sodium arsenate, as 

 in the following two formulae : (1) Anhydrous sodium arsenate, 3 parts 

 by weight ; neutral lead acetate, 9 ; water, 1,000 ; (2) anhydrous 

 sodium arsenate, 3 parts by weight ; neutral lead acetate, 9 ; copper 

 sulphate, 20 ; lime, 10 ; "water, 1,000. The followng are the four 

 zinc arsenite formulae given : (1) Zinc arsenite, 2| parts by weight ; 

 gelatine, |- ; water, 1,000 ; (2) zinc arsenite, 2^ parts by weight ; 

 copper sulphate, 20 ; lime, 10 ; water, 1,000 ; (3) zinc arsenite, 

 2h parts by weight ; Marseilles soap, 3 ; water, 1,000 ; (4) zinc 

 arsenite, 3 parts by weight ; Marseilles soap, 4 ; water, 1,000. The 

 trial of zinc arsenite in the vineyards is advocated. 



Tests of insecticides in experimental plots confirmed the great 

 efficiency of nicotined Bordeaux mixture and of wetting nicotine, 

 solutions, the high efficiency of pyrethrum, the lessened effectiveness, 

 of nicotine mixed with hme, and the inferiority of pyridine to nicotine. 

 In the treatment of large vineyards, nicotined Bordeaux mixture saved 

 a much greater value in grapes than the cost of this preventive treat- 

 ment. The work done with bait-traps is reported in detail, many 

 practical conclusions being reached [see this Review, Ser. A, ii, p. 359]. 

 The natural enemies of P. hotrana were an important control factor 

 in 1913 in the Sauterne district, where most of the author's obser- 

 vations were made. For about ten years this district had been a 

 centre of infestation, though little damage was done in 1913. Whilst 

 this has been attributed to the use of bait-traps, it is essentially due 

 to natural causes, such as the suppression of part of the first generation 

 owing to the premature emergence of many adults and the action of 

 natural enemies, including Ichneumonids and Malachius. An attempt 

 was made to acchmatise the parasites of the American vine-moth,, 

 Pohjchrosis viteana, Clem., and eight species of parasitic Ichneumonids. 

 were received from the U.S. Bureau of Entomology, a hst of which 

 will be pubhshed later. Only two species were numerous enough for 

 breeding purposes and one of these seemed to promise good results.. 

 Further trials are however necessary. 



