Banana fruit fly, Bactrocera musae Tryon is endemic to Australia and mainland Papua New Guinea (PNG) and remains an important pest in tropical orchards. B. musae is classified as polyphagous since it feeds on several families in Musaceae, Caricaceae and Myrtaceae while preferring banana as its primary economic host. Methyl eugenol was successful in trapping very high number of adults: primary forest (100%), secondary forest (99%) and cocoa plantation (94%). Abundance trapped with cue-lure was very low, 6% in cocoa plantation and 1% in secondary forest. Significant difference was detected between abundance in cocoa plantation and primary forest (p<0.01), and also with secondary forest (p<0.05). However, there was no significant difference between primary and secondary forest (p>0.05). The striking differences can be attributed to both biotic and abiotic factors, and their interactions. The population of B. musae demonstrated a dynamic pattern on a temporal scale (fig. 3). Our 6 months of intensive sampling detected the lowest population in June (159, 17.7±8.4, p<0.05) and the highest in October (620, 91.2±37.2, p>0.05). Wet season recorded higher numbers while high air temperature reduces the activity of adult B. musae. Host availability and fruiting season contributed positively to peak numbers of fruit flies. Finally, the height, canopy structure and different architecture of vegetation in primary and secondary forests provided a suitable resting site for adults of B. musae.