• Lake States Forest Experiment Station
  U.S. Forest Service
  

In order to obtain a reliable estimate of egg parasitism, nonviability, and hatch, all egg-mass collections are taken after hatching has been completed. Viable eggs, before hatching, are easily distinguished in the egg mass an can be readily counted, but the boundaries of the translucent chorions of the hatched eggs are almost indistinguishable, making it extremely difficult to count the individual egg shells. This study was undertaken to determine if the number of eggs per mass could be correlated with egg-mass length and/or width.