PHENOLOGY AND RELATIVE ABUNDANCE OF CEROPLASTES DESTRUCTOR AND CAMELLIA-SINENSIS (HEMIPTERA, COCCIDAE) ON CITRUS IN NORTHLAND, NEW-ZEALAND

The main scale insect pest in citrus orchards in Northland, New Zealan d was Ceroplastes destructor although C. sinensis was more widespread. We studied the phenology of both species over 3 years by regularly sa mpling scales on leaves and wood for laboratory examination. Both spec ies were univoltine. The start of C. destructor crawler emergence vari ed by c. 7 weeks over 6 years, and was inversely correlated with annua l degree-days. Egg hatching occurred c. 2 months earlier in C. destruc tor than C. sinensis. The development of successive instars continued to be earlier in C. destructor so it passed through the first and seco nd instar stages by autumn and 4 months faster than did C. sinensis. F irst and second instars are vulnerable to adverse weather and predatio n and their longer duration in C. sinensis may partly account for its lower abundance. We predict that control by insecticides should be mos t effective in late January for C. destructor and in late March for C. sinensis.