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 a person or 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.