Surveillance
DPW’s Mosquito team monitors Henrico’s adult mosquito populations across 100 sites within the county. The traps used to collect adult mosquitoes are not a form of control, but rather used for research and disease testing. The two types of traps used to attract mosquitoes are CO2 traps and gravid traps. CO2 traps use carbon dioxide and lures to attract blood-seeking mosquitoes. Gravid traps use a liquid bait to target egg-laying female mosquitoes.
The mosquitoes are identified by species and counted, and their numbers are recorded to monitor changes in local populations. Key species of interest to Henrico are those that are known carriers of West Nile virus. These mosquitoes are pooled and tested for the disease. Testing occurs from June through October. Lab results help focus treatment efforts to areas of potential threat. If there is a concern for public health, our department will notify our impacted residents.
Treatment
The mosquito team treats standing water on county property, easements, and right-of-ways. More than 400 sites in Henrico are monitored for the presence of mosquito larvae. We use a truck-mounted liquid larvicide applicator to treat mosquito habitats, such as roadside drainage ditches, stagnant water on County-owned lands, drainage culverts, and underground storm water pipes. Additionally, smaller areas are treated by hand with granular larvicide. Currently, Henrico’s mosquito team uses BTI, which is a widely available environmentally friendly larvicide, safe for people, animals, and plants.
