Abstract
Excretion of honeydew by a scale insect, Ceroplastes pseudoceriferus GREEN, reared on pumpkin fruit, was kept under observation during its growth and development. Frequency of excretion of honeydew-droplets rapidly decreased through the larval stages. On the other hand, the amount of a droplet of honeydew per insect weight remained constant throughout development. The feeding activity of this scale insect was therefore assumed to be high in the early larval stages. Diurnal rhythm of honeydew excretion was particularly remarkable in the younger stage. The maximum and minimum frequency of excretion were observed between 18:00-20:00 hours and 6:00-8:00 hours, respectively. Field experiments were carried out to examine the effects of several insecticides on the scale insect, C. pseudoceriferus, and an aphid, Myzus persicae SULZER. Number of honeydew-droplets detected on a paper sheet of a definite size was successfully employed as a criterion for the evaluation of insecticides on these insects.
