If you have access to male mosquitoes you can slide mount the genitalia to identify males of both species.  Alternatively there are some molecular markers that could be used.  It all depends on how many specimens you have and how certain you need to be on each one.  You could try the LUCID based key at

http://www.wrbu.org/keys/cp_cxsgs_a/culex%20of%20sw%20asia%20-%20adults.html

use  of molecular and morphometric analysis.

look at this:   http://www.scielo.br/scielo.php?pid=S0074-02762010000500012&script=sci_arttext

Yes I agree with Ephrem Abiy, you can use molecular and morphometric analysis.

Also il you have a male mosquitoes you can mounted the genitalia to identify the species.

Good luck

You can visit the Walter Reed Biosystematic Unit website (www.wrbu.org).  They have this interactive lucid keys that's quite neat.  you can also get tons of papers on taxonomy

Hello, this is Al-Amin from Bangladesh. In Dhaka quinque is the main mosquito. You can go through this: first look at the proboscis, if it does not have any pale scales and completely black there would be possible chance of quinque, fusco, hutch etc. Then look at the postspiracular area, there would be no pale scale. Abdominal terga 2-6 with semilunar shape basal pale scales. Do not confuse it with hutch. As I find that mesokatepisternum and mesepimeron is without the dark and pale pattern for quinque but hutch possess the pattern. Look at the keys of Bram: Contributions to the mosquito fauna of southeast asia II the genus Culex in Thailand. Also I think the attached figures would help.

Best of luck.

Al-Amin

-Cx quiquefasciatus is a golden yellow mosquito and about 4mm length

-proboscis, thorax, wings and tarsi are darker than the rest of the body

-abdomen has pale rounded bands on each tergite

- in Africa its a very domesticated mosquito biting indoors and outdoors and resting indoors after feeding

Qasim, I agree with Al-Amin and Samuel, including bright and dark scales on the occiput.

I send to you the key for Identification Cx quiquefasciatus in Vietnam.

The characteris for the Identification of Cx quinquefasciatus in Vietnam.

2

3

4

You can also consider using the identification keys found in the book " Mosquitoes of southern Africa" by Jupp. Has a lot of characteristics you can use to identify Culex quinquefasciatus.

The immature stages (eggs, larvae, pupae) of Culex Spp are shown in page 17 of the book of service (2008) and the latest edition. 

The adult culine makes a distinctive angle with the substrate where it is resting.

You may start a colony of culicines with larvae collected from the wild, based on the description of Service. After they emerge, you use the morphological features of the wings, head-thorax and legs given above to separate adult Culex quinquefasciatus. Be mindful of possible ecological variations so don't forget that these insects have remarkable adaptive radiation, mechanisms that can change even some morphological features over time and across a wide spatial range. Get some regional species to see if they correlate with species from other regions, here sequencing may help further.

After you have some key similarities, I may suggest that you confirm either with molecular or cytogenetics markers. It lsounds exciting to type culicines in your area.

Good luck and looking forward to a published masterpiece 

Dear Dr. Qsim Ali

Have visited

http://fmel.ifas.ufl.edu/key/index.shtml

http://fmel.ifas.ufl.edu/key/genus/culex_quin.shtml

here you would find good pics of  your organism

also search under

› Culex fatigan

› Culex fatigans

› Culex pipiens fatigans

› Culex pipiens quinquefasciatus

› Culex pipiens quiquefasciatus

› Culex quinquifasciatus

› Culex quinquifasiatus

› Culex pungens

good luck