Editing Diapause (section)

===Initiation===
[[Photoperiod]] is the most important stimulus initiating diapause.<ref name=Chapman404/> The initiation phase begins when morphological development ceases.<ref name="Kostal" /> In some cases, this change may be very distinct and can involve [[ecdysis|moulting]] into a specific diapause stage, or be accompanied by color change. [[Enzyme|Enzymatic]] changes may take place in preparation for [[cold hardening]]. For example, only diapausing adults of the fire bug, ''Pyrrhocoris apterus'', have the enzymatic complement that allows them to accumulate [[polyol|polyhydric alcohols]], molecules that help to lower their freezing points and thus avoid freezing.<ref>{{cite journal |last1= Kostal |first1= V. |last2= Tollarova |first2= M. |last3= Sula |first3= J. |year= 2004 |title= Adjustments of the enzymatic complement for polyol biosynthesis and accumulation in diapausing cold-acclimated adults of Pyrrhocoris apterus |journal= Journal of Insect Physiology |volume= 50 |issue= 4|pages= 303–313 |doi=10.1016/j.jinsphys.2004.01.006|pmid= 15081823 |bibcode= 2004JInsP..50..303K }}</ref> Insects may also undergo behavioural changes and begin to aggregate, [[insect migration|migrate]], or search for suitable [[overwinter]]ing sites.[[File:Angangueo monarchs.jpg|thumb|Overwintering [[monarch butterflies]] in diapause clustering on [[oyamel]] trees. One tree is completely covered in butterflies. These butterflies were located on a preserve outside of [[Angangueo]], [[Michoacán]], [[Mexico]]]]