none Phthorimaea operculella; AGE-; EGG-; Age & density, effect on acceptance to hymenopteran parasite; HYMENOPTERAN-PARASITES; Chelonus blackburni; Host egg acceptance, effect of egg age & density Chelonus blackburni; EGG-LAYING; Lepidopteran host egg acceptance; LEPIDOPTERAN-HOSTS; Phthorimaea operculella; Host egg acceptance, effect of egg age & density The response of an efficient egg-larval parasitoid Chelonus blackburni Cameron to different ages and densities of potato tuber moth Phthorimaea operculella (Zeller) eggs was studied in a laboratory system. The parasitoid accepted 0-1, 1-2 and 2-3 day old eggs for parasitization. However, the eggs belonging to the first two age groups were significantly more acceptable when compared to the last age group. At low host density levels of 2 and 5 eggs per parasitoid, parasitoid emergence was zero. On increasing the host density, percent progeny production increased till a plateau was reached at a parasitoid-host ratio of 1:50. This ratio thus proves to be ideal for obtaining maximum percent progeny production in the case of 0-1 and 1-2 day old eggs. Further increase in host density did not result in any significant increase in percent progeny production.