The effect of abamectin was evaluated on the functional response of green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), at seven egg densities of tobacco budworm, Heliothis virescens (Fabricius), and fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), using Holling s disc equation. Functional response of green lacewing was Type II, indicating that as prey density increased, predation rate also did. However, the predation rate of the three larval instars of green lacewing on tobacco budworm eggs was significantly less because of the insecticide effect, decreasing 48.0, 46.1 and 47.3% on first, second and third instar respectively. The same response was observed with fall armyworm decreased 64.5, 36.2 and 23.6% on first, second and third instar larvae respectively. Functional response parameters such as attack rate (a´), handling time (Th), total handling time (Tht), searching time (Ts), and search efficiency (E) were affected by reducing predation, causing a negative effect on predator behavior by increasing the time to identify and consume prey. This affected efficacy of green lacewing as a biological control agent.