218 



acid, at least in the case of tobacco in Deli. Insufficient mixing with 

 the diluent or unfavourable weather may account for this. To 

 ascertain the content of water-soluble arsenious acid 5 grms. of the 

 powder were placed in a 500 c.c. retort which was filled to the mark 

 with distilled water free from carbonic acid. The retort was rotated 

 for 1, 5, 25 and 125 hours at a temperature of 30° C. [86° F.] and the 

 amount of arsenious acid was then determined by titrating 100 c.c. 

 of the filtrate. It was found that whereas the percentage of arsenious 

 acid was 0'63 after 1 hour's rotation it increased to 8'49 after 125 

 hours. Tests with various samples of Paris green showed that some 

 of them parted with the acid more readily than others and that these 

 are the ones more hkely to scorch. The American method of boiling 

 Paris green in a solution of sodium acetate also yielded more arsenious 

 acid if the time was increased. In judging the quality of Paris green 

 it must therefore be remembered that the duration of the treatment 

 influences both the absolute and the relative result, and besides 

 ascertaining the amount of arsenious acid after 1 hour, it is necessary 

 to note the results after 2, 4, 6 and more hours. 



SiLVESTRi (F,). II Ceroplaste (o Cocciniglia) cinese degll Agrum!. 



[The Citrus Scale, Ceroplasfes sinensis,] — R. Lab. Entom. Agraria, 

 Portici, Boll. no. 2, 10th February 1919, 15 pp., 6 figs. 



About twenty years ago Ceroplastes sinensis was added to the list 

 of scale-insects infesting citrus trees in Italy and Sicily, having been 

 introduced a few years previously. A description is given of the 

 larva and adult. At Portici oviposition takes place from early July 

 to early August ; the young larvae begin to appear in the second 

 fortnight of July and some are still to be seen at the end of August. 

 The difierence between the sexes becomes apparent in the third stage 

 larvae. Some of the males pupate at the end of October and yield 

 adults in November, while others enter the pupal and adult stages at 

 the end of winter or early in spring. Most of the female larvae moult 

 in late autumn and become defijiite females of the fourth stage. Larval 

 development is Retarded in exposed situations and accelerated in 

 sheltered, warm positions. Thus, first-stage larvae may be found 

 early in winter or definite females may appear early in autumn. The 

 food-plant also influences development. It is advanced one stage on 

 Schinus molle and Veronica speciosa as compared with development 

 on citrus. C. sinensis has therefore one generation a year near Portici. 

 The more preferred food-plants are Schinus molle, Muhlenbeckia 

 plaly dados, Veronica speciosa, V. salicifolia, Chrysanthemum frutescens, 

 G. grandijlora, followed by the different kinds of citrus, Euonymus 

 japonica, Spiraea chaniaedry folia, Phyladelphus coronaria. Aster 

 formosissima, Dahlia variabilis and Salvia splendens. Gardenia florida, 

 Amarantus sp., rose, pear and apple have also been recorded as food- 

 plants, but it is probable that such infestations are accidental and 

 possibly are limited to the first-stage larvae, which may also be f oimd 

 on many herbaceous plants near infested trees. From July to Novem- 

 ber it is therefore advisable to avoid transferring kitchen-garden and 

 ornamental plants from infested localities to areas that are uninfested. 

 Like other Coccids, G. sinensis weakens the plant by sucking its juices 

 and its sugary excreta also favour the growth of sooty fimgus. 



