Year Start of the effective temperature Length of the effective temperature (days) Sum of effective temperatures (°C) Appearance of the first butterfly 2007 12, April 9 112 21, April 2008 7, April 8 105 15, April 2009 9, April 11 96 18, April

Table 2: Appearance of the first flies from overwintering pupae in relation to effective temperature in Gachsaran in year of 2007 – 2008.