Host defensive behaviors in parasitoids that are, including strong physical responses include (pre-oviposition reaction) and also physiological reactions that include (post-oviposition ones) are very important factors which can affect hardly host selection by them, foraging strategies and reproductive success of parasitoids. This research was conducted to examine defensive behaviors in the second and fourth instar aphids (black bean aphid, Aphis fabae Scopoli), (Order Homoptera: Aphididae family) when they were exposed to female wasps (i.e: Lysiphlebus fabarum) of the sexual strain population of parasitoid wasp Lysiphlebus fabarum (Marshall) (Family Braconidae: Sub family Aphidiinae). For this purpose, wemade synchronous cohorts population of the second and fourth instar stages of black been aphid were established, separately and carefully. Then, the parasitoid wasp that they were (1 day-old) and were reared on the second instar aphid (black been), were introduced separately into a patch that were consisted of 15 second or fourth instar host (aphis fabae, black been aphid). Then, the all defensive behaviors of aphids (Aphis fabae, black been aphid) were recorded for 30 minutes carefully and compeletly, by accure and continuous observations. The Results indicated that the fourth instar of Aphis fabae (black been aphid) had really very stronger defensive responses than what the second instars (i.e: Aphis fabae, black been aphid) did, especially in the frequency (number) of kicking behaviour. Against, second instar of A. fabae secreted more defensive droplets to respond to wasp’s attacks than fourth instar did; the finding suggests that cornicles secretions can be an adaptation response at this growth stage.