One evening during a recent survey by the Dragonfly Society of the Americas, there were between thirty and forty adults of ages from twenty to eighty walking, running, and twisting around in a quarter acre clearing in the woods, swinging insect nets over their heads. Most of the attempts resulted in empty nets. Similar events involving groups of similar size occur every summer across the United States, Canada, and many other countries. These participants are not novices. Many have been studying dragonflies and damselflies (odonates) for three to five decades. Yet, the frequency of capture for flying odonates is often less than five percent as the animals are capable of almost instantaneous evasion.
The Purpose of Surveys
Because these insects are large and beautiful, watching dragonflies and damselflies has recently become a focus of observers much as watching birds and butterflies have become. People are attempting to determine the numbers of species for towns, counties, states, and countries across the world. There are societies established to determine the names, both common and scientific, for odonates; others work to identify their distributions and the times of year that they can be found. Researchers investigate rates of parasitism and predation, reproductive efforts, and their habitat requirements.
Although more than 4500 species have been identified in the world, only 451 species are found in the United States. Because of odonate habitat and climate requirements, any state has only a small portion of the total species. There are 115 species of odonates in California, 170 in Florida, 11 in Hawaii, 177 in Alabama, 34 in Alaska, 136 in Rhode Island, and 153 each in New Hampshire and Connecticut. In Connecticut, New London county has 119 known species, 4 more than the entire state of California and over 80% of Connecticut's total, making New London the most completely surveyed county in the state. Yet because habitats are quite varied and unevenly distributed throughout the county, the species number in any town falls far short of the county total.
Often, participants in surveys are novices, and expect their roles in the survey to be minimal. Yet, of the forty or so species of odonates collected by one group of four rather novice members in the recent Northeast Regional Survey, seven species were first records for the towns in which they were captured, and fourteen species were new to some member of the group.
Reasons for Watching Odonates
There are hundreds of reasons why people chase and catch dragonflies. Among them are:
- Many are beautiful - odonates are sometimes called the jewels of the insect world.
- The total number of species is only estimated – the descriptions of two probable new species in the Northeast are currently being examined. One of these has widespread distribution across the United States and Canada. The other is found only along a short stretch of the Hudson River in the state of New York.
- Odonate distribution changes in different weathers and climates – some require cool weather, others need warmer days.
- The presence of dragonfly larvae indicates habitat quality – pollution, predators, and filling in wetlands can eradicate them. Eliminating insect-hunting dragonflies may increase the incidence of mosquito-transmitted diseases.
- Capturing dragonflies is a challenge – almost impossible to do while they are hunting.
- Some are extremely arduous to identify – while their colors are variable and usually change dramatically within a week of emerging, seemingly insignificant differences distinguish some species.
- Just finding some dragonflies may be challenging – the names of bog haunters, stream cruisers, the pine barrens bluet, and seaside dragonlet describes their preferred habitats.
The Benefits of Dragonflies
Adult dragonflies and damselflies are among the top daytime aerial insect predators. Swallows and swifts may capture as many insects (including many dragonflies), but these birds do not have the agility and finesse of the odonates. A dragonfly can stop in mid flight, drop its tail, and fly 90º upward to capture a mosquito.
Larval dragonflies (nymphs) live underwater and breathe via gills. They are equipped with a hinged lower jaw that shoots out, pierces a small fish, tadpole, or other insect, and pulls it back to be eaten. Some lie in ambush, others crawl or swim through submerged vegetation. Odonates may stay in the nymphal stage from two months to five or six years, depending on water temperatures and the size of the adult, feeding all year - even under the ice in winter.
Are Dragonflies Dangerous?
Although a successful hunt spells death to the unwary insect, and despite being called "darning needles," "devil's needles," "snake doctors" (because people thought they brought snakes back to life), and other dangerous sounding names, dragonflies pose no problems to humans. They do not sew lips or eyelids shut, sting (even though males have long abdominal extensions and often curl their tails forward when caught), or even bite humans. They attempt to bite if a finger is pushed into their mouths, but the bite of the largest is a slight pinch that feels like scratching the skin with a fingernail. Large nymphs pinch only slightly harder.
In many cultures, dragonflies are eaten either raw or cooked. No diseases are known to be transmitted to humans after eating dragonflies. Although they may be tasty, the benefit to humans provided by live odonates eating insects far outweighs the benefits that an individual may obtain by eating them, and these aerial acrobats should be allowed to hunt their insect prey unmolested.
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