430 



Del Guercio (G.). Results of the First Experiments with Polysulphides 

 strengthened with Flour Paste in the Control of Chrjjsomphalus 

 diciyospermi var. pinnulifera on Citrus Trees. — Mtlily. Bull. Agric. 

 Intell. & PI. Dis., Rmne, vi, no. 3, March 1915, pp. 474-475. 

 [Abstract from Riv. Patologia vegetale, Pavia, vii, no. 5, 

 pp. 129-135.] 



In this prehminary report of spraying experiments made in 1914 

 for the control of Chrysomphalus dictyospermi var. pimmlifera, Mask., 

 it is stated that the addition of 1 or 2 per cent, of flour paste, fish glue, 

 etc., increased the efficiency of the polysulphides employed. At 

 present, rye flour answers best, being inexpensive and most tenacious, 

 but damaged wheat or other flour can also be successfully used. 

 Insecticides thus prepared always wet completely and uniformly. 

 The protecting shields of the scale-insect remain as if glued to the 

 plant, so that the larvae and eggs perish beneath the mother scale. 

 The most active polysulphide is that of potash, even in amounts of 

 less than 1 per cent, for the control of the laivae, and at from 5 to 7 

 per cent, for the adult scale ; in July, its action on the adults 

 is apparent from the second day, while the larvae are killed almost 

 instantaneously. This polysulphide, when strengthened with flour, 

 owes its increased destructive power to its remarkably hygroscopic 

 nature ; during the night and early morning it absorbs moisture from 

 the air, and its injurious efl'ects on the scale-insects are renewed, while 

 during the day and until night-fall its action is lessened. This circum- 

 stance is most fortunate, since it is thus easy to avoid scorching and 

 injury from the sun's rays, which readily takes place in the southern 

 parts of Italy and especially in Sicily. The liquid, however, loses its 

 efficacy if the plants are washed by heavy rains immediately after 

 spraying. Polysulphide of soda is much less efl'ective than the potash 

 compound ; the impurities which accompany it also prohibit its use. 

 Polysulphide of lime, alone, does not adhere well to very young shoots 

 and leaves, or to green branches or fruit ; it adheres better to old 

 citrus leaves, but never wets 1 hem evenly. Even when strengthened with 

 glue or flour, it has never the swift eft'ect of polysulphide of potash, 

 nor is it so efficacious, being deficient in the latter's hygroscopic 

 property and not giving rise to the same chemical changes. On the 

 other hand, it retains its protective property longer, since it is less 

 easily washed off by rain. Double polysulphides strengthened with 

 flour were obtained by mixing together the polysulphides of potash 

 and lime, plus the viscous substance. These mixtures possess the 

 properties mentioned in the case of their ingredients. Organic poly- 

 sulphides prepared from polysulphide of potash and soap are apparently 

 as efficacious insecticides as polysulphide of potash with flour paste, 

 but their protective action does not last so long. 



The following papers are abstracted from the Bolletino del Lahoratorio 

 di Zoologia Generale e Agraria delta R. Scuola Sup. d^ Agric. in Portici, 

 Portici, 1914-1915, ix. [Eeceived 21st April 1915.] 



Mahtelli (G.). Notizie su due Coccinellidi micofagi. [Notes on two 

 mycophagous Coccinelhds.] — pp. 151-160. 



Both Halyzia {Thea) 22-2)unctata, L., and Halyzia {Vibidia) 12-guttata, 



