This study was conducted to see the initial increasing time of population of citrus leafminer(CLM) in spring and early summer seasons in 2007-2011. CLM adults were monitored using sex pheromone trap which is mainly composed of Z,Z-7, 11-hexadecadienal in the 4, 8 and 5 orchards of the east, south and north part in jeju island, respectively during 2007-2011 seasons. The traps and lures were changed at 10 days and 1 month interval, respectively. Though CLMs were captured on traps from March or April, it was 17, 28 and 28 May in 2007, 16, 26 May and 5 June in 2008, 8, 26 and 26 May in 2009, 27 May, 7 and 7 June in 2010 and 25 May, 2, 2 June in the south, east and north part of Jeju Island, respectively that the CLM population rapidly began to increase toward peaking. The accumulated temperature except less than developmental zero, 12.1 Ujiye T 1990). from January was 248.0, 270.5 and 289.7 in 2007, 193.2, 203.8 and 261.4 in 2008, 202.0, 245.5 and 259.9 in 2009, 261.4, 192.2 and 268.3 in 2010 and 243.4, 246.3 and 252.4 in 2011 at that time. After May overwintered CLM adults are little possible to be counted to the number of captured CLM because adult longevity is about 100 in degree days (Lim 2006). CLM populations in the south part of Jeju Island in first CLM adults increasing periods during 2007-2011 is higher than other parts.