Ochlerotatus triseriatus is primarily a vector for La Crosse Encephalitis and is usually found in which habitat?

• A. Usually found in tree rot cavities and is the primary vector for La Crosse Encephalitis.
• B. Found in urban storm drains and not a vector for La Crosse.
• C. The primary vector for West Nile Virus.
• D. Feeds only on mammals and not humans.

Answer: (A)

Ochlerotatus triseriatus, known as the eastern treehole mosquito, thrives in natural water-filled cavities in trees. Because its larvae develop in tree holes, its natural habitat is wooded areas where these cavities are common. This association with tree hole habitats is exactly why it is the primary vector for La Crosse Encephalitis: the virus circulates in this species within those natural containers and can be transmitted to people who encounter the adults in those environments.

The other options don’t fit as well because urban storm drains are more typical breeding sites for other mosquitoes, often linked to different viruses like West Nile, and this species is not the main West Nile vector. It also does not feed exclusively on mammals; it readily bites humans as well as other animals, so the mammals-only notion isn’t accurate.