Dragonflies are said to be a “sentinel” species; their presence provides insights into the health and pollution levels of wetland areas. Just as canaries were used in mines to determine levels of harmful gases for miners, the presence (or absence) of dragonflies can give us clues about how degraded our ecosystems are and whether harmful chemicals or pesticides are present.
Dragonflies, similar to mosquitoes, lay their eggs in standing water. The resulting larvae (or nymph) can live underwater for up to six years, depending on the species. Dragonfly nymphs have voracious appetites and mosquito larvae are an important part of their diet – they can eat the equivalent of their body weight in food in about thirty minutes. Moreover, according to recent studies, mosquito larvae actually stop developing when in the vicinity of dragonfly larvae. Another interesting fact is that dragonfly nymph molt up to fifteen times before reaching the adult stage, and this is why methoprene and other pesticides are so deadly to them.
More than fifty years ago, Rachel Carson was the first scientist to recognize the significance of sentinel species. Carson was a profound writer and cutting edge scientist; her work launched the environmentalist movement. By exposing how chemical corporations were using propaganda and scare-mongering tactics to sell chemicals, Carson became the target of attacks that sought to demean the science and her character. Sound familiar? Rachel Carson said, “the ‘control of nature’ is a phrase conceived in arrogance, born of the Neanderthal age of biology.” Rachel’s book Silent Spring exposed how chemical pollutants impact ecosystems, threatening species with extinction and impacting human health.
Photo Credit: Rachel Carson
Today, as Carson predicted, we live in an environment with far less habitat and as a result fewer predators and increasingly weakened coastlines. Additionally, we are in the throes of climate change. To meet future challenges, we need a revised and science-based approach to develop radical habitat restoration programs that will protect our coastlines and wetlands, which serve as buffer zones between us and sea level-rise.
Support legislation for an official day that New York State celebrates wetlands:
An annual “Dragonfly Day” on the 2nd Saturday of June. Set this day aside to enjoy group hikes, participate in citizen science studies by spotting dragonflies and exploring local wetlands and learn about what you can do to help increase biodiversity so we can check mosquito populations using predators- not deadly chemicals.
Find out more about Nature-Based Solutions for healthier environments HERE