A female marl pennant, an unusual species that breeds in brackish ponds and often along the coast, perches in Ocean Ridge. Jerry Lower/The Coastal Star
See more photos of dragonflies
By Cheryl Blackerby
Here’s one reason to love dragonflies: They eat mosquitoes. Lots of them. One can eat hundreds in a day.
Dragonflies probably are not as popular as butterflies as a recreational pursuit, but their beauty and diversity are just as mind-boggling — from the cobalt-blue spangled skimmer to the brilliant scarlet skimmer, as red as a fire engine, and the hot pink roseate skimmer.
They’re easy to spot since Florida has more than 150 species of odonates, which include three families of damselflies and six families of dragonflies. They’re found near water at all times of the day, especially the cocktail hour when the mosquitoes emerge. More importantly to scientists, dragonflies are an excellent gauge of the health of the environment.
“They are really good indicators of high-quality wetland environments, which usually mean a greater diversity of damselflies and dragonflies.
They seem to be susceptible to those problems that damage wetlands such as degradation by herbicides and runoff from agriculture fields,” said Jaret Daniels, associate curator of Lepidoptera at the Florida Museum of Natural History at the University of Florida.
“Many dragonflies are declining because of declining wetlands,” he said.
He has noticed increased interest in dragonfly watching. “They’re showy and popular for viewing,” he said, adding that it will take patience finding one that will pose long enough to snap a photo.
Big eyes and strong bodies
Dragonflies are fascinating creatures. The have six legs but can’t walk. They can perch and fly, and mate while flying. Their front pair of legs is shortest and the back longest. “The legs form a large net for capturing prey,” Daniels said.
Their bulging compound eyes are made up of many smaller lenses that greatly magnify the movement of their prey and make them excellent visual hunters. Their eyes take up nearly the entire head.
A strong body supports a massive musculature that propels the large broad wings that are transparent or elaborately patterned. Wingspans range from 2 to 5 inches. Unmatched as fliers, dragonflies are studied by engineers who calculate how they hover like helicopters and propel themselves in six directions — upward, downward, forward, back, right and left.
Damselflies and dragonflies are similar but their differences are easily distinguishable.
“Damselflies are more dainty, and they hold their wings over their backs, unlike dragonflies that hold their wings straight out. Damselflies have vibrant colors, iridescent black and opaque colors. They tend to perch and are easy to watch.”
Male dragonflies are generally more colorful. “There are shades of gray, blue, and red, and they may have bands of colors on wings,” he said.
They live adjacent to aquatic environments and lay eggs in the water. The eggs hatch into naiads. When a naiad is ready to metamorphose into an adult, it climbs out of the water. The skin splits behind the head and the adult dragonfly crawls out of it larval skin. Its four wings come out, and they dry and harden over the next several hours to days. Lifespans range from a few weeks to a year.
Dragonflies are often seen over large blacktop parking lots, which experts think they mistake for open bodies of water.
Besides mosquitoes, they also eat flies, ants and wasps, and they themselves are preyed upon by birds, lizards, frogs, spiders and fish.
Coastal residents can’t plant flowers to attract dragonflies as they do to draw butterflies. But a steady supply of mosquitoes along with healthy wetlands will keep them coming.
“We encourage people to watch them. They’re so unique and amazingly beautiful creatures,” Daniels said.
And there is only one way to protect them, and that’s protecting Florida’s wetlands, he said.
Dragonfly facts
• Large dragonflies such as hawkers have a maximum speed of 22–34 mph, with an average cruising speed of about 10 mph.
• There are more than 5,000 known species of dragonflies.
• Dragonflies were some of the first winged insects to evolve, some 300 million years ago. Fossil dragonflies have been found with wingspans of up to 2 feet.
• Scientists have tracked migratory dragonflies by attaching tiny transmitters to wings with a combination of eyelash adhesive and superglue. They found that green darners from New Jersey traveled an average of 7.5 miles per day.
• A dragonfly called the globe skinner has the longest migration of any insect — 11,000 miles back and forth across the Indian Ocean.
— Smithsonian Institution
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