SEASONAL PREVALENCE OF THE ARROW-HEAD SCALE (Unaspis yanonensis KUWANA) IN NAGASAKI PREFECTURE (3)

Observation of the first instar larvae of the arrow-head scale was made every 5 days at 13 stations in Nagasaki Prefecture from May to September in 1964.In 1964, the appearance of the larvae of the scale was earliest in these years of 1962-1964. This early appearance might be resulted in the high temperature in March and April in 1964.Dates of the first appearance and the peak of appearance of larvae of the first generation in each station were shown in Table 1. The earlier appearance was observed at the stations situated in southern part of Shimabara Peninsula. The later appearance was seen at the stations in northern part and islands in this prefecture. At the stations of Omura, Nagayo, Shimabara, Mogi and Ishida (Iki Island), the number of the second generation was as many as that of the first generation. From these results, following 4 areas was recognized tentatively concerning forecasting of the scale occurrence: (1) the southern part of Shimabara Peninsula and Nomo Peninsula (17℃ or more in annual mean temperature), (2) the northern part of Shimabara Peninsula and the coast of Omura Bay (16°～17℃ in annual mean temperature), (3) Isahaya City and the mountaincous region of Matsuura province (15.5°～16℃ in annual mean temperature), (4) the islands situated in the northern prefecture, respectively.