Dragonflies of Florida: Among the Most Primitive, Beneficial, and Beautiful InsectsSep 22, 2022 11:36AM ● By William R. Cox
Observers of the dragonfly cannot help but appreciate its beauty, phenomenal agility, displays, and speed of flight. It is among the most beautiful of insects and is one of the most beneficial as it feeds on mosquitoes, gnats, and other nuisance insects. Often called the mosquito hawk, the dragonfly is a voracious predator in both of its life stages as an aquatic nymph and an adult.
A dragonfly’s body is encased in an exoskeleton. It has three body sections: a head with two large eyes and two small antennae; thorax with four wings and six jointed legs; and abdomen with 10 segments and two or three terminal appendages.
The dragonfly belongs to a large insect order called the Odonata. Within this taxonomic order are two suborders: the Anisoptera (dragonflies) and Zygoptera (damselflies). Damselflies differ from dragonflies in that they are less robust and hold their wings folded over their backs instead of out to the side like dragonflies.
Odonates represent one of the most primitive living insect orders. Their earliest fossils date back 250 million years. The probable ancestors of Odonata, the order Protonata, lived more than 300 million years ago. Some had wingspans greater than two feet.
In the 19th and 20th centuries, there were just a few naturalists and enthusiasts studying Odonates. At the start of the 21st century, there was a tremendous increase in interest in these amazing insects mainly because of Sidney Dunkle’s 2000 publication of Dragonflies through Binoculars: A Field Guide to Dragonflies of North America. This was the first field guide for dragonflies used by scientists, enthusiasts, and nature photographers, and it led to the phenomenon of dragonfly-watching that is even more popular today. This was followed up in 2020 with a publication popular in Florida, Dragonflies of Florida, written by James L. Lasswell and Forrest L. Mitchell. This waterproof pamphlet illustrates 80 of the 120 dragonfly species in Florida.
Worldwide there are some 5,500 species, approximately 433 in North America north of Mexico and 120 in Florida. More than 40 percent of the dragonfly species that reside in Florida range over the entire peninsula. Others are restricted in their range depending on temperature and available habitat.
Dragonflies have three major habitat regions in Florida. The first area is the northern one-sixth of the peninsula. Approximately 15 percent of these dragonfly species do not range farther south than Gainesville. The second area is the middle half of the peninsula between Gainesville and Lake Okeechobee, which is the southern extent of the sandy central Florida ridge. This is where infertile, clear-water, and sand-bottomed lakes are found, as well as where streams flow. Approximately 30 percent of Florida’s dragonfly species inhabit this part of the state. The third major area is the subtropical southern one-third of the peninsula from below Lake Okeechobee south to the tip of Florida. This includes approximately 15 percent of Florida dragonfly species. The Dry Tortugas and the Keys harbor only a few dragonfly species because of a lack of freshwater wetlands on the islands.
Water is fundamental to the dragonfly’s life cycle. After mating, it lays its eggs near or in streams, lakes, ponds, canals, ditches, marshes, and other wetlands. Eggs can be killed by mold and eaten by aquatic mites. Those that survive hatch into aquatic nymphs in about 10 days, though the time span varies from five days to several months specific to each species. Nymphs eat many species of invertebrates and small fish. In turn, nymphs are eaten by fish, frogs, turtles, and birds.
A nymph sheds its exoskeleton, depending on the species, eight to 16 times during a period of one month to more than two years. When a nymph crawls out of the water and holds itself above the surface on emergent vegetation, an internal metamorphosis occurs transforming the nymph into a winged adult. The adult emerges out of the nymph exoskeleton. This transformation takes several hours, and the insect is vulnerable during this time to preying ants and blackbirds, as well as strong wind and waves.
The dragonfly is harmed by many human activities that impact streams, lakes, ponds, and other wetlands. Dragonfly nymphs are killed by pesticides, organic wastes, sewage, fertilizer, and silt. Fertilizer and grass-clipping runoff from yards causes algae blooms and bacterial growth that depletes oxygen. Soil erosion from deforestation and other types of land clearing blocks light, decreasing aquatic vegetation growth and destroying the bottom characteristics of a water body. It is critical that dragonfly habitats have 20 to 30 meters of forest and other vegetation buffer zones to reduce poor water quality and excessive hydrological impacts.
Dragonfly-watching is an enjoyable and fascinating hobby that will increase your appreciation for this beautiful insect. I encourage you to pursue it.
William R. Cox has been a professional nature photographer and ecologist for more than 35 years. Visit him online at williamrcoxphotography.com.