Mosquito Production on Abandoned Properties

Stephanie Richards, PhD, Medical Entomologist

Mosquito control programs can use a variety of surveillance-based tools for helping reduce mosquito populations, including:

  • Source reduction (e.g., removing artificial containers)

  • Water management (e.g., removing debris from ditches to help improve drainage)

  • Biological control (e.g., mosquito fish)

  • Larvicides

  • Adulticides

Did the financial downturn lead to more mosquitoes?

The financial downturn that has occurred during the past decade has contributed to the depression of the housing market in some regions of the United States. As the rate of home foreclosure increases, the possibility of abandoned properties may increase. In addition, construction at some sites may have been halted before completion due to funding restrictions or other reasons, hence resulting in potential mosquito issues. This can happen when forested area is cleared for construction of a new neighborhood but not graded for house plots, leaving water-holding ruts that are mosquito egg-laying sites.

Abandoned Swimming Pools

In some residential neighborhoods, homeowners with swimming pools may stop maintaining (e.g., removal of leaves) or chlorinating the pools due to foreclosures or other (e.g., health, financial) reasons. In other cases, pool owners simply stop maintaining their pools during times when the pools are not frequently used (e.g., fall/winter). However, depending on the geographic region, mosquitoes may be active year-round. This lack of maintenance may result in swimming pools becoming hot spots for mosquito production for both Culex (e.g., vectors of West Nile virus) and container-inhabiting Aedes mosquitoes (e.g., vectors of Zika virus) species in neighborhoods.

Abandoned and Neglected Property

Furthermore, neglected properties are not well maintained and can become overgrown with vegetation, hence, providing harborage for adult resting mosquitoes. Additional mosquito egg-laying sites may become available if the abandoned grounds are used for dumping trash and have other abandoned water-holding items (e.g., tires, plant pot receptacles).

Some counties and/or municipalities have implemented pool mitigation programs due to the mosquito problems (and associated citizen complaints) linked to abandoned or unmaintained pools. The extent to which environmental and/or public health officials can enforce the maintenance or appropriate closure (filling in) of residential pools depends on the existing rules and regulations in that location. In some counties and/or municipalities, existing ordinances explicitly require residents to prevent areas of standing water that may promote mosquito production. If there are existing ordinances, mosquito control personnel (e.g., environmental health, public health, public works) may be tasked with inspecting properties, reporting their findings and contacting homeowners about any mosquito-related issues. In some cases, citations may be issued to homeowners that are not in compliance after a designated period of time (e.g., 30–60 days). These regulations and potential enforcement measures vary widely among different counties and municipalities.

Pool mitigation programs may involve filling in abandoned or neglected swimming pools with dirt or concrete so they no longer hold water, remediating/fixing issues with pools so they function correctly, treating pools with larvicides (must be repeated over time) or implementing biological control (longer-term solution) by introducing mosquito fish into the pools. In most cases, homeowners are responsible for funding this mitigation, and local programs may assist in the mitigation process.

A large, unmaintained water-holding swimming pool is capable of producing thousands of mosquitoes that could impact public health and the ability of neighbors to enjoy time outside in their yards. Property values in a neighborhood would certainly be negatively impacted if mosquito-related issues (nuisance biting and/or mosquito-borne disease such as West Nile virus or Zika virus) are present. Consequently, homeowners’ associations may consider keeping track of abandoned properties in neighborhoods, especially if the properties have unmaintained swimming pools. Mosquito control and/or public/environmental health agencies can be contacted for help if a mosquito production site is suspected.