Crystallization of CaC03 accompanying chemical absorption of C02 as a single gas and as a mixture with S02 into aqueous solutions of Ca(OH)2 was studied in a stirred vessel with a flat gas-liquid interface. The nucleation and growth rates determined by CSD analysis of crystals formed in a MSMPR crystallizer were related to several operating conditions. The type and shape of the crystals varied with the concentration of Ca(OH)2, but their mean size was only slightly influenced by the concentration of Ca(OH)2 and by the mean residence time of suspension. The presence of S02 considerably reduced the growth rate of CaC03 crystals under the conditions of a slight decrease in the rate of C02 absorption.

A serious citrus pest, the ash whitefly, Siphoninus phillyreae Haliday, was first recorded in Honshu and Kyushu, Japan. The favored host plant is pomegranate (Punica granatum L.) from early summer to autumn. The adults migrate to a hedge plant (Photinia glabra (Thumb.) Maxim.) or rarely to a citrus plant (Citrus natsudaidai Hayata) before pomegranates shed their leaves in winter. Another citrus pest, the woolly whitefly, Aleurothrixus floccosus Maskell, was found from Nansei Islands to north of Tokunoshima Is., Japan. The distribution of these two pests and diagnostic features were detailed. Substrate-borne vibratory sounds produced during mating were elucidated, including new findings of male and female communication by reciprocal sound signals. It is suggested that the species-specific bioacoustic signals preserve useful information for the whitefly biosystematics of economic importance.

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