Ascher, K.R.S., Divisions of Toxicology, Volcani Center, Bet Dagan, 50-200, Israel
Nemny, N.E., Divisions of Toxicology, Volcani Center, Bet Dagan, 50-200, Israel
Ishaaya, I., Divisions of Entomology, Agricultural Research Organization, Volcani Center, Bet Dagan, 50-200, Israel

The mortality rates of Spodoptera littoralis eggs of different ages when dipped in aqueous dilutions of a liquid diflubenzuron formulation were investigated. Eggs 2‐3 days old were less sensitive than younger eggs, 0‐1 day old. The respiratory rate of eggs 0‐1 day old, 1 or 2 days after treatment, was the same as in the control. Eggs in the control hatched on the next day; on this day, respiration in the treated eggs decreased rapidly, but further decrease was then gradual and the base line was not reached until 11 days after treatment, or 9 days after the maximum respiratory rate had been obtained. The curve with diflubenzuron resembled that obtained with parathion. Copyright © 1980 John Wiley & Sons, Ltd