There are 4 stages in total.
1) Egg stage:
After the female mosquito has fed she will find a quiet place to rest and develop her eggs. It may take several days.Once she is ready to lay her eggs she will find out an appropriate place. The place which is selected and the way the eggs are laid largely depends on the genus. If she is in the Aides genus then she will most likely lay her eggs simply on the edge of a drying puddle or near the surface of water. If she is in the Culex or Culiseta genus then she will lay her eggs in a raft on the surface of water. Each raft will contain several hundreds of eggs. She will repeat this cycle of obtaining blood meals and laying eggs until she dies.
2) Larval stage:
Because the larva's skeleton is located on the outside, similar to that of a crab, they must shed their exoskeleton in order to grow. All mosquito larvae shed their exoskeleton, or molt at least 4 times. The stages between molts are called in-stars. The newly hatched larvae are called first in-star larvae. They are very small and hard to see. Mosquito larvae float on the surface of water so that they can obtain food and breathe through their siphon. The siphon is located at the base of their abdomen and is similar to a snorkkel. The larvae feed on bacteria and other organic matter in the water. The brush like structure that are located in front of their mouths collect the food.
3) Pupal stage:
After the larvae have completed their 4th in-star stage they become pupae. This is the stage in which they undergo metamorphosis to become an adult mosquito. The process is similar to a caterpillar which is about to become a butterfly. The pupae are very active and can move very quickly through the water unlike other insects. They look like commas. The mosquito is a pupa for only a couple of days. The pupae are transparent and we can see the developing adult inside the pupal case.
4) Adult stage:
After 1-3 days the adult mosquito is ready to start its life. The pupal skin splits along the top of the case. The adult mosquito slowly and carefully works its way out of the pupal case. After emerging it floats on the surface of the water and rest there until its body and wings start to harden. Once the body is hardened, the mosquito is ready to fly off to begin its new life.
Hope dis ans will help u :)