Some species also feed in daylight hours and others day and night. The blood sucking habit is what causes mosquitoes to become a vector for disease. If a female mosquito feeds for example on the blood of a malaria carrying person, the disease organisms survive and reproduce in the mosquitoes, ending up in her salivary glands. Next time she feeds on a new host, she inoculates her new host. Seasonal Abundance Mosquitoes may breed at any time from spring to the first frost.
Populations are generally highest in summer and early fall.
When rain is abundant, many species can lay eggs continuously and with ideal temperatures a cycle can be completed inside one week. Medical Importance Worldwide mosquito play an important role in diseases, like malaria. In the US they are more like a nuisance. Human mosquito transmitted diseases remain relatively rare and are generally limited to encephalitis among humans and dog heartworm among dogs. At least six types of mosquitoes transmitted encephalitis occur in the United States.