There are more than 3,500 species of mosquitoes worldwide. However, not all mosquitoes suck blood. Some mosquitoes live without sucking blood. Additionally, not all mosquitoes that suck blood from humans and transmit diseases. Many mosquitoes suck blood from other organisms, such as birds and cows .
There are three main species of mosquitoes in the world that carry disease-causing pathogens: Anopheles, Aedes, and Culex; even among these, only post-mating females transmit diseases (Fig. 1). So, why do post-mating female mosquitoes need blood? It is to raise eggs. Female mosquitoes usually mate only once with a male . To lay eggs after mating, female mosquitoes search for hosts and suck blood, which is a good source of protein. After blood-sucking, they cease their activity to raise eggs in their body. Next, they find a clean water source to spawn. After spawning, the process of sucking blood begins again, and the cycle is repeated.
Female mosquitoes lay 100 eggs at a time and more than 500 eggs in their lifetime.
When the egg matures, it becomes a larva called a wriggler. After that, it becomes a pupa, emerges as an adult in approximately 2 days, and leaves the water (Fig. 2).
 Thiemann TC., Wheeler SS., Barker CM., Reisen WK. (2011) Mosquito host selection varies seasonally with host availability and mosquito density. Plos Negl Trop Dis, 5: e1452
 Duvall LB., Basrur NS., Molina H., MacMeniman CJ., Vosshall LB. (2017) A peptide signaling system that rapidly enforces paternity in the Aedes aegypti mosquito. Curr Biol, 27:3734-3742