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the number of larvae by washing them down to the ground, where 

 they perish, but may carry infested leaves to considerable distances. 

 Wind must however be held to be the most important agent in diffusion. 

 Branches isolated by rings of cotton from the infested portion of a plant 

 were found to be infested after a certain time if the wind was blowing. 

 The importance of wind-carriage is evident from the fact that plants 

 sheltered from the wind are the most strongly infested, as a larger 

 number of larvae are left on them. Strong wind and rain together 

 act by carrying the larvae in the rain drops, as has previously been 

 noticed by Del Guercio in the case of Ceroplastes sinensis, D. G. 



A list of 56 food-plants is given, including the following : — Acacia 

 hngifolia, A. retinoides, Arbutus andracline, Callistemon sp., Citrus 

 aurantium, C. deliciosa, C. Umomwi, C. sinensis, Cycas revohda, 

 Eriohotrya japonica, Euonymus europaeus, E. jajjonicus, Ficus stipu- 

 lacea, Hedcra helix, Kentia sp., Melaleuca sp., Metrosideros sp., 

 Miihlenbeckia platyclados, various species of palms, Pandanus gramini- 

 folia. Phormium sp., Strelitzia reginae and Zea mays. Observations 

 on these plants show that C. dictyospermi can develop and attain 

 maturity on them. The Coccid was seen on some other species, but 

 though the larvae became attached on them, they died at a certain 

 stage, probably because the juices were not suitable. This was 

 noticed on the grape vine, peach and apricot, which in Sicily are 

 cultivated promiscuously with citrus plants. C. dictyospermi was 

 never observed on them when they were at a considerable distance 

 from the citrus trees. They are therefore not true hosts and may be 

 transported without any risk of spreading infestation. Nor is there 

 any risk in the transport in winter of deciduous plants of which the 

 leaves alone are subject to attack. It was found that the natural 

 mortality among larvae in favourable conditions amounted to 5 per 

 cent, before fixation. In late autumn, however, especially in rainy 

 weather, eggs which had dried up and dead larvae were observed under 

 the mother's shield. After fixation, early in June, larvae 15-20 days 

 old showed a natural mortality of 5-10 per cent. Later on, the adult 

 female mortality was 2 per cent., increasing to 15 per cent, in October 

 and 25 per cent, late in November, at which time the mortality of 

 adult males was 40 per cent, and that of larvae and nymphs 19 per 

 cent. These figures were allowed for in estimating the value of 

 insecticides. 



The economic importance of C. dictyospermi in Italy varies in different 

 regions ; at the present time the extensive citrus groves of Sicily 

 and Calabria are the most menaced. This pest was introduced into 

 Italy without its natural enemies. None have been foimd either in 

 Liguria or Tuscany, and during 1913 and 1914 the authors noticed 

 very few endophagous or predaceous species in Sicily. According 

 to De Gregorio, Aphelinus silvestrii, De Greg., exercises useful control. 

 The predaceous species destroy not more than 10 per cent, of the 

 adult Coccids and the endophagous species are even less efficient, for 

 only one Chalcid nymph was found in about 30,000 Coccids examined. 

 In America, Aspidiotiphagus citrinus is a parasite of C. dictyospermi, 

 while Aphelinus chrysomphali is reported to be useful in the Iberian 

 peninsula. Cultural methods of control include pruning and 

 defoHation. Pruning is valuable because a properly pnmed tree 

 offers less shelter to the Coccid against unfavourable climatic factors. 



