DEVELOPMENT AND MORTALITY OF THE CITRUS SNOW SCALE (HOMOPTERA, DIASPIDIDAE) UNDER CONSTANT-TEMPERATURE AND RELATIVE-HUMIDITY

Citrus snow scale development was studied under 9 combinations of cons tant temperature and relative humidity An effect of temperature and re lative humidity on the rate of development was observed. Optimal tempe ratures for development ranged between 25 and 38 degrees C and develop mental thresholds were estimated at 12 degrees C. There were no differ ences in developmental time between sexes, nor on values of sex ratio between temperatures. Development on grapefruit leaves reported here w as faster than that reported previously for development on lemon fruit s. A nonlinear model of development was fit to the stage duration data and a gamma distribution model was fit to the mortality data.