none The paper deals with the behaviour of Lysiphlebia mirzai , an aphidiid parasitoid of the pearl-millet aphid Rhopalosiphum maidis , at varying host densities. By increasing the host density on the leaf of the food plant Pennisetum typhoides , the parasitoid showed the following responses: 1. Host-searching time (leaf- and host-arrival time) significantly decreased curvilinearly; 2. the frequency of host contact with the ovipositor (stabbings or prickings) and oviposition into the hosts, first escape time and total retention period with the host increased exponentially; and 3. the ratio of stabbing and oviposition decreased curvilinearly. Reproduction; Reproductive behaviour; Reproductive productivity; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Ecology; Population dynamics Lysiphlebia mirzai (Braconidae); Oviposition; Rate; Egg number; Hemipteran host density effects; Hemipteran hosts; Rhopalosiphum maidis; Parasite behaviour, effect of host density; Host seeking; Prevalence; Rhopalosiphum maidis (Hemiptera) density effects Rhopalosiphum maidis (Aphidoidea); Hymenopteran parasites; Lysiphlebia mirzai; Parasite behaviour, effects of host density; Host seeking; Prevalence; Lysiphlebia mirzai (Hymenoptera), host density effects; Population density; Hymenopteran parasite behaviour relationships