The effects of the chitin synthesis inhibitor lufenuron againstpotato tuber moth, Phthorimaea operculella (Zeller), eggswere determined by topically exposing different age groups of eggs(1–4 d old) to treated potato tubers (Solanum tuberosum L.)under laboratory conditions. Larval hatch from both treated (4 and12 g [AI]/100 liter) and untreated tubers was >95%, butmortality of first instars was high in treated tubers (>90%) comparedwith untreated tubers. Examination of the treated tubers showed thatmost of the larvae were unable to penetrate or cause any noticeabledamage to the potato tubers. However, the few first instars thatsurvived were able to penetrate the tubers and continue theirdevelopment to the pupal or adult stages. At 12 g (AI)/100 liter,adult emergence was <2% and most of the emerged adults hadmorphological deformities such as reduced wing size and they wereunable to free themselves from the pupal sacs. These data suggest thattopical application of lufenuron to eggs before larval hatch wouldreduce the amount of damage caused by potato tuber moth as part ofintegrated pest management program.