Even though there is no consensus on the exact factor(s) responsible(s) of the onset and the ending of the diapause, one accepted hypothesis for the modeling purpose is the Lipid Accumulation Window where the concentration of the lipids reserves will determine the duration of dormancy (Ohman et al. (1998) [11], Johnson et al. 2008, Maps et al. (2011) [12]). As soon as the numerical species have accumulated enough lipids (determined by a specific C:N ratio) to survive until the next spring it will stop its lipids synthesis and go into diapause. Then the next year, as soon as their lipid reserve is used (low C:N ratio) they will end their diapause and resume an active metabolism.