Mosquitoes are very diverse with around 3,500 different species distributed over the whole world except Antarctica and a few islands.
Within the eco system, mosquitoes are a part of the food source for animals such as fishes, frogs, birds, or bats.
But for humans and many other animals they are one of the deadliest animals in the world. Their ability to carry and spread diseases to humans causes more than 400.000 deaths every year.
Reason: though both male and female mosquitoes feed on nectar and plant juices to get their energy, in many species the females additionally need nutrients from a blood meal for egg production. By feeding on blood from different hosts, the mosquitoes become vectors of parasites and infectious pathogens between humans, or from animals to humans. Vector-borne diseases include malaria, dengue fever, yellow fever, West nile fever or Zika which are mostly distributed in the tropical and subtropical regions.
There is a great variety of mosquito behaviour regarding blood hosts: Some mosquito species have
specialized in specific hosts, whereas others bite anything they encounter.
One thing all mosquitoes have in common is that they spend their immature stages in the water.