Dragonflies & Damselflies

Class: Insecta
Order: Odonata
Suborder: Anisoptera
Family: Various

Most people are familiar with dragonflies. They're the large and fast flying insects that you see zipping along the edges of ponds, lakes, and streams on warm summer days. Most are skinny, have large wings and are brilliantly colored. Dragonflies are the most skilled fliers in the insect world -- they're also among the most ancient.

Dragonflies belong to the insect order Odonata, which includes a closely related group of flying insects called damselflies. They have existed in their current form for approximately 200 million years (much older than any dinosaur). The largest of the ancient Dragonflies had a wingspan of 75 cm -- that's 2 1/2 feet!! It would have been interesting to see a predatory insect flying around that was bigger than most of our birds.

Trickster med

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Life Cycle

Dragonflies have three stages of life: egg, nymph, and adult. The length of each stage depends on the species of dragonfly. Dragonflies in tropical regions typically spend less time in each stage than dragonflies in regions like Minnesota. After mating, usually in mid-to-late summer, the female dragonfly lays her eggs on submerged aquatic plants, mud banks submerged in water, or - if they can't find a better spot - directly in the water. Dragonfly eggs are only laid in still water, as eggs laid in quickly moving water will wash into fish-feeding areas. Depending on the species, a female can lay hundreds or thousands of eggs during her lifespan. The eggs hatch in the spring time when the weather is warmer.

When dragonflies hatch they are called nymphs. Dragonfly nymphs are voracious predators that have no resemblance to their adult forms. They molt (shed their skin) up to 12 times, depending on the species, and can spend as long as four years as nymphs. Dragonfly nymphs are aquatic, living in ponds and marshes until emerging to molt one final time. During the final molting, the nymph's skin splits and the nymph emerges as an adult dragonfly. Dragonfly nymphs are hemimetabolous, meaning they don't form a cocoon or pupate before emerging as an adult.

After the final molt from nymph to adult (which occurs in late spring or early summer), most dragonfly species spend the next month fully maturing. Their color becomes brighter with their final markings, and they disperse - sometimes hundreds of miles - from the pond or marsh where they developed. Adult dragonflies are also voracious predators, eating small insects, primarily mosquitoes and flies, which they catch while flying. Dragonflies can hover and can fly backwards, forwards, and sideways. Both female and male dragonflies only live two to four months as adults before dying.

Source: Sciencing 
Dragonfly Molting Video
Dragonfly molting final nymph skin to become adult.
Adult dragonfly on top of nymth skin that it just motled.
Dragonfly_Foodweb
Dragonfly nymph eating a small fish.
Dragonfly eating a mosquito.

Energy Web

Dragonfly nymphs and adults are carnivorous and are top predators in many aquatic food webs. As nymphs, the dragonflies eat mosquito larvae, other aquatic insects and worms, and for a little variety even small aquatic vertebrates like tadpoles and small fish. The adult dragonfly uses the basket formed by its legs to catch insects while flying. They like to eat gnats, mayflies, flies, mosquitoes and other small flying insects. In one 30-minute time span, a dragonfly can eat an amount of food equal to its own weight!

As secondary consumers, juvenile and mature dragonflies play a role as food for higher level animals. In the aquatic larval stage, their primary predators are ducks, amphibians such as toads and newts, fish, and bigger damselfly and dragonfly larvae. When the nymphs sense danger, they often attempt to dodge predation by pretending to be dead or by swimming away quickly. When predators clutch onto them, nymphs can escape by allowing their limbs to fall off. These limbs grow back during molting. The nymphs evade predation by hiding among plants as well.

Adult dragonflies must dodge a broad assortment of predators, specifically arthropods, reptiles, fish such as bass, tiny mammals such as water shrews, frogs, and fellow insects.

Source: Minnesota Dragonfly Society

Habitat

Dragonflies live more than half their lives in water and are found in every type of freshwater habitat: large lakes, small wetlands, and all sizes of streams. They are typically found in and around aquatic vegetation, although some groups prefer to hang out on the bottom of streams among the rocks and leaf litter.

Because of their beauty and their "showy" nature, dragonflies have caught the attention of people throughout human history. As a group, they are probably the most recognized insects behind butterflies. For this reason, dragonflies are known by many common names, some of the more interesting ones include mosquito hawks, devil's darning needles, snake doctors, snake-tails, biddies, club-tails, darners, skimmers, and emeralds. There are many more interesting names, but far too many to list here.

Dragonflies, in addition to being interesting and beautiful, are also quite diverse. There are approximately 650 known species from North America and 5,500 worldwide. Because of their diverse nature, dragonflies occupy a wide range of habitats and display a wide range of sensitivities. Several dragonflies, due to their requirements for very sensitive, limited habitats, are either in decline, threatened or on the endangered species list. Some are already extinct.

Source: MN Pollution Control Agency
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