Plant mapping has been used quite extensively in recent years with various objectives. The objective of this study was to demonstrate the effect of insect infestation on site-specific boll retention and the subsequent plant response to boll loss. In 1999, two different colonies of tobacco budworm larvae, USDA at Starkville, MS (MS-TBW) and NCSU (NC-TBW), were used in separate trials to infest an experimental Bt cotton (MXB5) and a non-Bt check (Jajo9550). At the end of the season, 10 consecutive plants per rep were mapped for the presence or absence of bolls. The mapped data from the paired insect infested plots were compared differentially to that from the insect controlled plots. Both the MS-TBW and the NC-TBW larvae reduced the boll set of the Jajo9550 check, most notably at the 1 ^st position bolls. MS-TBW infestation reduced 1 ^st position boll set of Jajo9550 about twice that observed for NC-TBW and it reduced the boll set of 2 ^nd position bolls from node 6 to 13. Jajo9550 partially compensated for the MS-TBW induced boll loss with higher boll set at 2 ^nd position bolls above node 13 and at 3 ^rd positions. Jajo9550 fully compensated for the lower NC-TBW induced loss at 2 ^nd and 3 ^rd position bolls. Both colonies slightly reduced the boll set on MXB5 at position 1 from nodes 10 to 15, but this loss was over-compensated for at other sites to yield more under insect infestation.