Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 4 2 2010 12 15 42 49 EN H Dehghan Department of Medical Entomology and Parasitology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran J Sadraei Department of Medical Entomology and Parasitology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran SH Moosa-Kazemi Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2015 10 03 Background: Culex pipiens complex shows variations in morphological and biological characters including differ­ent biological forms and has medical and veterinary importance. Because of having morphological variations, some­times it is not easy to separate this species from Cx. quinquefasciatusand Cx. torrentium.The aim of this study was to  identify the  Culex pipiens complex species in order to use in control programs in the future. Methods: This study was carried out in two randomly selected rural villages in Yazd County, eastern Iran using dip­ping technique from April to October 2009. The data were analyzed using SPSS software version 16. Results: Average of siphon index in fourth-instrar larvae was 3.86±0.03, the minimum and maximum were calculated 2.43 and 5.14, respectively. Siphon/Saddle index was measured as average, minimum and maximum 3.2±0.2, 2.78, and 4.42 respectively. In our study, only 4 specimens had single seta 1 on segments III and VI (2.5%) and the remaining beard double seta (97.5%). The maximum 3-6 branches seta 1a-S and 1b-S (95%) were observed on siphon. Conclusion: More populations of Culex pipiens from different areas of Iran need to be studied to gain complete informa­tion about the taxonomy and ecology of the species in the country. https://jad.tums.ac.ir/index.php/jad/article/view/72 https://jad.tums.ac.ir/index.php/jad/article/download/72/70