Laboratory investigations into the effect of host movement and host substrate on ovipositor-probing behaviour in Psyttalia concolor (Szepligeti) were conducted. Ceratitis capitata (Wiedemann) (Diptera Tephritidae) fully-grown larvae were used as hosts, while the host substrate was represented by an alfalfa meal-based medium. Five treatments were carried out, using an oviposition dish containing: (1) both mobile host larvae and medium, (2) only mobile host larvae, (3) only medium and (4) only immobilized host larvae, with (5) an empty dish serving as a blank control. Results showed that significantly more P. concolor initiated oviposition-probing behaviour in dishes containing both mobile host larvae and medium (100%); in contrast, significantly fewer wasps probed dishes containing host larvae alone (43.3%) or only medium (13.3%). The proportion of P. concolor probing dishes containing only mobile larvae was significantly higher than dishes containing medium alone. There was no significant difference among proportions of wasps probing dishes containing medium alone (13.3%) or immobilized larvae (6.7%) or empty control dishes (3.3%). Therefore, a combination of both mobile host larvae and host substrate induced the highest level of probing responses in P. concolor, suggesting that more than one cue is necessary to elicit the optimal response. Moreover, the finding that mobile larvae induced a higher level of ovipositor-probing behaviour than immobilized larvae suggests that host movement likely played a major role in eliciting ovipositor probing behaviour in P. concolor. Reproduction; Reproductive behaviour; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts Ceratitis capitata (Tephritidae); Hymenopteran parasites; Psyttalia concolor; Host movement & substrate role in parasite ovipositor probing behaviour Psyttalia concolor (Braconidae); Egg laying; Ovipositor probing behaviour; Dipteran hosts; Ceratitis capitata; Host movement & substrate role in parasite ovipositor probing behaviour none