The present work realized a comparative study in meiosis of two triatomines,Panstrongylus herreri and P. megistus, by cytogenetic techniques involving the restriction endonucleases Hae III andAluI and C-banding. The system of sex chromosomes inPanstrongylusis of the XXX2Y type, and experiments corroborated the common origin hypothesis of the X chromosomes by fragmentation of single X. In both species the restriction endonucleases (RE) presented banding patterns in part similar to C-banding. However, in some early meiotic phases it was possible to verify differentiation of the heterochromatic pattern. This work sug-' gests that other elements besides presence of recognition sites, such as chromatin packing degree and DNAprotein interaction, act in RE results, since digestion patterns occur in early spermatogenesis. However, metaphase chromosomes were practically inaccessible to the endonucleases.