The seasonal abundance of the common larval and
adult species: Culex pipiens, Cx. quinquefasciatus and Cx. sitiens was
examined in four sea ports (Jeddah, Yanbu, Duba
and Haql) and two cities (Taif and Mecca) representing
the three regions of the western part of the Kingdom (Mecca, Al Madinah and
Tabouk) based on larval density (number per a survey unit, SU each of 10 dips)
and adult density (number per a trap). Larvae were collected by dipping and
adults by CDC, Black Hole and UV light traps biweekly from January 2013 to
December 2014. The compiled density of the two years for each species in the different
localities and in all localities altogether was calculated. Cx .pipiens larvae
breed all year round with peaks of abundance were during autumn in Taif (78.02
larva / SU), summer in Jeddah (38.59 larva / SU), spring in Tabouk (10.61 larva
/ SU) and autumn for all areas altogether (21.63 larva / SU).  Cx. quinquefasciatus larvae breed all
year round with peaks of abundance were during winter in Jeddah and Yanbu
(128.92 and 36.04 larva / SU in the two localities, respectively) and for all
areas altogether (34.54 larva / SU).  Cx.
sitiens larvae breed all year round in Jeddah, with peak of abundance was
in summer (77.67 larva / SU).  Cx.
pipiens adults were active all year round with peaks of abundance  during autumn 
in Taif , Mecca and Yanbu (4.68, 4.97 and 3.96 adult / trap,
respectively) and spring in Tabouk, and all areas together (9.50 and 5.36 adult
/ trap, respectively). Cx. quinquefasciatus adults were active all year
round with peaks of abundance in spring in all localities either separately (Taif:
11.07, Jeddah: 31.22, Yanbu: 1.93 and Tabouk: 7.78 adult / trap) except Mecca
with peak during autumn (11.31 adult / trap) or in all areas altogether (11.06
adult / trap). The obtained results are of importance in predicting the period
of maximum risk of bancroftian filariasis, Wuchereria bancrofti and West
Nile Virus transmission and for carrying out an effective control program.