475 



The mixtures used were 10 parts soap-pyrethrum to 90 parts of 

 Bordeaux mixture, and 100 parts of Bordeaux mixture to one-fourth 

 part nicotine extract titrated to 50 per cent, alkaloid. The next 

 day 92 per cent, of the larvae were dead on the vines treated mth 

 pyrethrum, and 44 per cent, on those treated with nicotine. The 

 action of nicotine, however, is slower and finally produced a total 

 mortality of 60 per cent, after several days. These tests confirm the 

 value of Bordeaux mixtures with pyrethrum-soap against the first 

 generation of P. hotrajia, and their superiority o\'er nicotine as a direct 

 insecticide. 



In reph' to a remark concerning the difficulty of procuring pyre- 

 thrum, an editorial note states that the plant has been cultivated in 

 the Botanical Station since 1894, and seems to be well adapted to the 

 climate of the coast of Algeria ; it grows without any attention, and 

 could be cultivated on all agricultural estates. 



Barge (J.). L'Emploi du Jus de Nicotine centre les Insectes. — Rev. 

 Agric. Afr. Nord, Algiers, xix, no. 104, 29th July 1921, p. 585. 



There are various brands of nicotine juice sold commercially which 

 require dilution before they can be used as sprays. A 1 per cent, 

 solution of nicotine must be diluted with five to ten times its volume 

 in water ; for higher strengths of nicotine the volume of water is 

 proportionately increased. It is well to add a solution of f lb. commer- 

 cial soda cr\'stals and 2 lb. of soft black soap in 200 gals, of water 

 to every 20 gals, of the weaker solution or 10 gals, of the stronger. 

 For certain larvae, and the more resistant Aphids, about 1|- pints of 

 methylated spirit should also be added. For fumigation in green- 

 houses, nicotine extract [10 per cent, nicotine] should be diluted by 

 five times only its volume in water, adding 2 lb. soda crystals per 

 gallon of extract ; or 1, 2 or 4 lb. per 5 gals, of juice containing 1, 2 or 

 4 per cent, nicotine. The liquid is heated in a boiler and then sprinkled 

 on bricks or iron sheets heated to a high temperature. The fumes 

 should be allowed to act for several hours. 



Pol TIERS (R.). Le Deperissement des Agrames cause par les Tetra- 

 nyques. [Withering of Citrus Trees caused by Tetranychus.] — 

 Progres Agric. & Vitic, Montpellier, Ixxvi, no. 31, 31st July 

 1921, pp. 117-118. 



The cultivation of Citrus in France is limited and localised owing 

 to the climate ; the lemon in particular, with which this paper chiefly 

 deals, is almost entirely confined to the region of Mentone, where 

 the citrus industry is of great importance. The trees are greatly 

 injured by the attacks of mites, particularly Tetranychus telarius, L., 

 and, to a less degree, T. !afiis, C. & F., and T. pilosus, C. & F. 

 The mites oviposit on the lower side of the leaves, near the veins, 

 and weave a silken web under which they live and feed. After a 

 short time the growth of the leaves ceases ; they turn yellow, dry up 

 and fall, and the death of the branch follows if nothing is done to 

 check the pest. Hot, dry weather is very favourable to the mites, 

 and they appear at Mentone each year about June (or May in very 

 dry seasons). The fruit also frequently harbours colonies of the 

 mites, which produce on it brown scars due to a sort of chlorosis, 

 caused by their gummy secretions. Fruit thus attacked falls from the 

 tree before maturity. 



(4286) 2 I 2 



