PHYSICAL DYNAMICS OF THE NONCLEIDOIC EGG OF STEPHANITIS PYRIOIDES (HETEROPTERA, TINGIDAE) DURING DEVELOPMENT

Overwintering feral eggs of the immigrant azalea lace bug, Stephanitis pyrioides (Scott), and eggs laid on plants in a rearing chamber were sampled over time and measured for changes in size and weight during d evelopment. Eggs collected from both sources that were incubated in a rearing chamber were found to increase significantly in width and brea dth. For eggs laid in the rearing chamber the greatest rate of change occurred between days 2 and 4 of embryo development, whereas in the fe ral eggs it occurred between Julian days 51 and 82. Although a cubic r elationship was significant between day of embryo development and widt h and breadth for rearing chamber eggs, a quadratic relationship was s ignificant between Julian day and width and breadth for feral eggs. Me asured length of rearing chamber eggs did not change over time, but th e length of feral eggs increased linearly with Julian day. An increase in weight of feral eggs was linearly related to Julian day and the me an weight of eggs laid in the rearing chamber was quadratically relate d to day of embryo development. Excised leaves with feral eggs were sa mpled biweekly during periods of dormancy and spring growth. It was de termined that adequate moisture was present in the leaves for the embr yo to complete development. Because number of days to preemergence was significantly influenced by Julian day (i.e, sampling date), the mean number of nymphs to emerge at each particular sampling day was not si gnificantly influenced by moisture or day. The significant increase in egg width, breadth and weight indicates that the egg of S. pyrioides is noncleidoic and that the chorion is both pervious and elastic. A po ssible impact on voltinism is discussed.