Effects of dormant oil on FTC hatching

To determine the effects of temperature and dormant oil on hatching FTC the following experiment was set up April 4th on 40 egg masses collected last summer. Sixteen egg masses were sprayed with a dormant oil labeled for use on FTC egg masses. All others were not sprayed. Each egg mass, containing approximately 300 eggs, was placed in a window-pane envelope. Then the egg masses were either kept at room temperature or kept outdoors in the shade.


Percent of FTC that hatched and lived
 Not sprayedSprayed with oil
Indoors100%0 %


  • At room temperature, most FTC hatch within 14 days.
  • Dormant oil spray is useful in preventing FTC from hatching and can kill most of the caterpillars that do hatch.