Gronotoma micromorpha is a solitary egg-pupal and larval-pupal parasitoid. In a previous study, the developmental time of this parasitoid decreased with the age of its leaf miner host, Liriomyza trifolii, being significantly longer when the host was 0-day old (= 0-24 h old egg) than when 4 days old (mature larva) at the time of parasitization at 25°C. In the present study, the suitability and acceptability of 0 and 4 day old L. trifolii as hosts for G. micromorpha, and the ovipositional preference of this parasitoid for these two developmental stages of the host were examined. No significant difference was found in the size of the parasitoid offspring that emerged from hosts parasitized at these two developmental stages. There was no significant difference in the acceptability of the two developmental stages of L. trifolii in no choice tests, but 4 day old larvae were preferred to 0 day old eggs in choice tests. Moreover, parasitization of eggs by G. micromorpha did not appear to result in more of the eggs dying before they hatched. Non-reproductive killing (host feeding and host stinging without oviposition) of host eggs by this parasitoid was also not detected.