Survival of fireflies in urban communities is threatened by many factors:
- Pesticides and chemicals in lawns: Indiscriminate use of insecticides can kill many insects that are not the intended pests to be controlled by the insecticides. This includes fireflies. Adult fireflies can be killed by insecticides that are sprayed directly on them or when they get in contact with insecticide residue on the grass or leaves. One step in conserving fireflies is to limit the use of insecticides during the time of firefly activity.
- Pollution - water, soil, light: Pollution of water and soil, which the fireflies depend on for survival, can kill fireflies. The sources of pollution include chemical (pesticides, fertilizer, detergents, and other chemicals) and biological pollutants. Light can also be a source of pollution; strong, bright light can outshine the flashing and interfere with the mating behavior of fireflies.
- Land use pattern and habitat changes: Changes in land use patterns alter the native habitat of fireflies. Fireflies prefer wet and shady areas to lay eggs, rest and develop. Development of forested areas into open lawns or residential gardens can dry out suitable habitats and reduce the habitat of fireflies.
- Forest management: Forest management practices, such as harvesting, winter burning or brush clearing can significantly change the structure of the canopy and the physical properties of the environment, thus reducing the habitats of fireflies.
- Drought and other environmental changes: Drought and other significant weather events can change the conditions of a firefly habitat.
Firefly as Ecosystem Indicators – An environmental indicator is used to communicate information about ecosystems and the impacts of human activity to groups such as the public or government policy makers. The indicator can reflect a variety of aspects of ecosystems, including biological, chemical, and physical characteristics. The researchers at Clemson University are studying firefly as environmental indicator for coastal South Carolina. The unique bioluminescence property of fireflies provides visual clues of environmental quality and is easy to measure and quantify by the general public.
Fireflies are charismatic and reliable indicators of environmental health because their population density is correlated to the availability of healthy habitats (Kazama et al., 2009). A good firefly habitat is one that is moist, and contains large amounts of natural organic matter (Wu and Perng, 2007). The habitat of fireflies is significantly impacted by urban development. For example, converting forested areas into open lawns, residential gardens, and agricultural fields can change the structure of suitable habitats (Kazama et al., 2009; Juson et al., 2010). Indiscriminate use of insecticides in lawns and urban areas can kill many non-target insects, including fireflies. Pollution from commonly used chemicals (e.g., pesticides and fertilizer) and biological pollutants (e.g., pet waste) could also alter the quality of the habitat (Lee et al., 2008; Leong et al., 2007).
Light can also be a source of pollution (Viviani et al., 2010). Strong, bright light such as light from homes and cities can outshine firefly flashes and interfere with firefly mating behavior. All of these factors work together to reduce the quantity and quality of suitable habitats, thus reducing the number of fireflies. Therefore, the occurrence of fireflies provides a visual clue on the quality of the natural environments.
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Wu and Perng 2007. Formosan Entomologist 27: 31-45.
Jusoh et al. 2010. Wetlands Ecology and Management 18: 367-373.
Viviani et al. 2010. Biota Neotropica 10” 103-116.