The diploid number of chromosomes in two species of family pentatomidae Halys dentatus and Coridius janus is 14 (2n=14=12A+XY), with XY- male sex determining mechanism in both of the species.Autosomes show gradation in size, X is of medium size while Y is the smallest element. Both X and Y are positively heteropycnotic in diffused stage but become isopycnotic in diplotene/diakinesis stage and divide equationally during meiosis I, At metaphase II, X and Y get associated, the association being strong forming a pseudobivalent XY in Coridius janus while weak in Halys dentatus. A definite pattern of arrangement of the chromosomes is seen at Metaphase II where in autosomes formed almost a circle and the sex chromosomes forming a pseudobivalent, were observed in the centre of this circle.
