Mosquitoes are small blood-sucking insects that depend on standing water to reproduce. Female mosquitoes must feed on blood to lay eggs. They feed by sticking their mouthparts into the skin of an animal, and rapidly sucking blood. Sometimes mosquitoes carry germs like viruses that can be transmitted to a person while the mosquito is feeding. Preventing mosquitoes from breeding and avoiding mosquito bites are the best ways to avoid getting these diseases.