  We show that correlators of some local operators in gauge theories are
sensitive to the presence of the instantons even at high temperature where the
latter are bound into instanton-anti-instanton "molecules". We calculate
correlation functions of such operators in the deconfined phase of the 2+1
dimensional Georgi-Glashow model and discuss analogous quantities in the
chirally symmetric phase of QCD. We clarify the mechanism by which the
instanton-anti-instanton molecules contribute to the anomaly of axial U(1) at
high temperature.
