A period of suspended development or growth occurring in many insects and other invertebrates during which metabolism is greatly decreased. Some long-lived species may undergo diapause as adults, but for many others the egg or pupa is the diapausal stage. In temperate-zone animals, diapause is typically triggered by changes in day length that presage the onset of winter; and prolonged exposure to low temperatures may be the cue to trigger the resumption of development. In other climatic regions, adverse conditions can also trigger diapause. Both strategies enable the animals to survive unfavourable environmental conditions so that their development may continue in more favourable ones. The peptide, diapause hormone, is known to initiate diapause in embryos of the silkworm, Bombyx mori, but also to terminate diapause in some other moth species, as does the hormone ecdysone.