Abstract
Morphometric traits of adults of the oriental chinch bug, Cavelerius saccharivorus, in relation to its wing polymorphism were investigated in newly emerged adults collected from a high density population of the 1st generation in a ratooned sugar cane field. The frequency distribution of relative wing length (RWL) of adults showed a bimodality with brachypterous and macropterous forms, although it was not completely discrete because both forms showed considerable variation in this trait. Genetic differences in density responses among individuals within a population was considered to be primarily responsible for such a large variation of relative wing length. Complete macropters (RWL≥5.0) were on average larger in body length and had much more developed mesothorax than brachypters. However, incomplete macropters (RWL=4.5) were smaller in body length than brachypters with RWL of 4.0 and had a mesothorax which was intermediate between brachypters and complete macropters. Despite their intermediate morphological traits, they were regarded as macropters from behavioural, physiological, and genetical evidence.
