- Aedes triseriatus, commonly known as the Eastern treehole mosquito, is a mosquito species native to eastern North America and is best known as the primary vector of La Crosse encephalitis virus (LACV). This mosquito has adapted to breed in natural tree holes and artificial containers holding stagnant water, making it a key species in both forested and suburban environments.
- Its ecological niche and vector competence have made it an important species in the study of arbovirus transmission and mosquito behavior in temperate climates.
- Morphologically, Aedes triseriatus is a dark brown to black mosquito with silver or white scales on its thorax and legs. It exhibits a typical Aedes appearance but can be distinguished by the three distinct longitudinal stripes on the scutum (hence the name “triseriatus”). Adults are medium-sized and exhibit a preference for resting in shaded, humid environments, such as woodlands and forest edges. The species is diurnal, with peak biting activity during early morning and late afternoon hours. Female mosquitoes are aggressive biters, targeting both humans and animals, including squirrels, chipmunks, and other small mammals—key reservoirs for the La Crosse virus.
- Aedes triseriatus breeds primarily in tree holes, where water accumulates after rainfall. However, it is highly adaptable and readily lays eggs in artificial containers such as discarded tires, buckets, and other man-made water-holding items, especially in residential areas near wooded habitats. The eggs are resistant to desiccation, allowing them to survive dry periods and hatch when water becomes available. Larvae are filter feeders, developing in nutrient-rich, shaded waters, often alongside other mosquito species.
- One of the most significant aspects of Aedes triseriatus is its role in the transmission of La Crosse encephalitis virus, a mosquito-borne arbovirus that primarily affects children in the Midwestern and Appalachian regions of the United States. While most infections are asymptomatic or mild, some can result in serious neurological illness, including seizures, coma, and long-term cognitive damage. The virus circulates in a zoonotic cycle involving Ae. triseriatus and small mammals like chipmunks and squirrels, with humans serving as incidental hosts. Remarkably, this mosquito can also transmit the virus vertically, from female mosquitoes to their offspring through infected eggs, allowing the virus to persist in mosquito populations even in the absence of vertebrate hosts.
- In addition to LACV, Aedes triseriatus has shown laboratory competence for other arboviruses, such as West Nile virus and Eastern equine encephalitis virus, although its natural role in spreading these diseases is limited compared to other mosquito species like Culex pipiens or Aedes albopictus. Nonetheless, its ecological overlap with invasive mosquito species raises concerns about interactions that could influence disease dynamics, such as competition for larval habitats or potential hybridization.
- Control of Aedes triseriatus relies on eliminating breeding sites, particularly tree holes and artificial containers. In forested or rural areas, this can be challenging, but community-based interventions—such as public education, larviciding, and environmental sanitation—can significantly reduce mosquito populations in suburban areas. Personal protection measures, including the use of repellents, long sleeves, and screens, are also important in reducing bite exposure, especially for children in high-risk regions during the summer months.
