Physiological characteristics of diapause were studied in the lady beetle, Harmonia axyridis PALLAS. In the aestivating adults, the respiration rate decreased remarkably, but the body weight increased and mating behaviour and oviposition actively continued. This indicates that aestivation occurs at a reduced energetic state and not at a diapause state. In hibernating adults, reproduction was completely suppressed and the corpus allatum atrophied. Topical application of juvenile hormone analogue immediately induced ovarian maturation. Electrophoretic analysis of the heaemolymph of hibernating adults showed protein bands specific to diapause. These observations indicate that the hibernation of H. axyridis is a true diapause controlled by corpus allatum, and that their dormancy differs to that of Coccinella septempunctata bruckii MULSANT.