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The Dragonhunter(Hagenius brevistylus, shown right) refuses to let go of its meal, a Prince Baskettail (Epitheca princeps, on left)

Not too surprisingly, dragonflies seem to be everywhere on the arboretum in the summer. The diversity of habitats on campus allow for a diversity of species including common pond species, but also rarer stream and L. Michigan species. Dragonflies are classified in the suborder Anisoptera in the insect order Odonata along with the suborder Zygoptera or Damselflies. Dragonflies are an extremely successful group of insects and have been around for a long time. Fossils of the largest dragonflies, with wingspans of 30 inches, are known from Permian rocks that are 250 million years old, and were the largest insects. The largest North American species living today is a Hawaiian species (Anax strenuus) with a 7.5 inch wingspan. The oldest known species, Delitzschala bitterfeldensis, lived over 300 million years ago, but unlike some of its younger relatives was small with a wingspan of less than 2.5 inches. There are dragonflies on every continent, except Antarctica, and in nearly every aquatic habitat.

Why dragonflies have managed to survive for so long is probably due to the fact that they are extremely effective generalist predators. Jill Silsby, who wrote Dragonflies of the World says that "several adaptations, including the development of large compound eyes, wings that move independently of one another, and a highly streamlined body shape, all of which have made odonates superb hunting machines." Certainly the dragonfly that preys on other dragonflies might be considered the most superb of these hunting machines. Hagenius brevistylus, the dragonhunter, feeds on other odonates.

The dragonfly genus Hagenius contains only 1 species in North America, with its nearest relatives inhabiting Japan and India. They are found throughout the United States. The adults are large bodied with long wings and legs that allow them to capture other large fast flying insects. As its name implies, it does capture other dragonflies, but it also feeds on butterflies, and a variety of other insects. They are found throughout the United States, but you are more likely to see them in northern Wisconsin or Michigan than in the southern parts of the Great Lakes area.

Female dragonflies lay their eggs on or near water. Tiny nymphs hatch and crawl down to the bottom where they prey on small invertebrates or sometimes small fish. Unlike the adults, all dragonfly nymphs are dark colored to blend in with the dead leaves and other debris. They use this to their advantage to surprise unsuspecting prey. When a meal approaches the dragonfly's hinged lower jaw-like mouthpart (the labium) (called the mask in Odonates) reaches forward and scoops up the prey. The rate at which the nymphs molt and grow depends largely on temperature. Some species in the northern Great Lakes region may spend 3 to 7 years as a juvenile in the water. Once they are mature the nymphs crawl out of the water onto a stem or rock and they molt one last time into an adult dragonfly. It is easy to misidentify newly emerged winged dragonflies, or tenerals, because they are very soft and usually have very bright in color. As the exoskeleton hardens the adults will gain their true coloration.

dragonhunter teneral

A Hagenius brevistylus teneral.

Note the large abdomen and bright green color compared to the adult shown below.

Hagenius brevistylus.

Hagenius larvae are easily recognized from other dragonfly as larvae by their wide, circular, flat bodies and long splayed legs. This shape probably allows them to more effectively hide in the leafy debris in stream bottoms, protected marsh or pond habitats. The adults have black faces with large green eyes and a yellow thorax that is broadly striped with black. The abdomen is black with yellow markings and the distinctive clubtail found in most dragonflies in the Gomphidae family. The legs and the wing veins are black.

Odonata found on the Cofrin Arboretum

(list provided by Joan Berkopec and Ron Eichorn)

  • Dragonflies (Anisoptera)
    • Anax junius (Common Green Darner)
    • Aeshna canadensis (Canada Darner0
    • Libellula pulchella (12-spotted Skimmer)
    • Libellua luctuosa (Widow Skimmer)
    • Plathemis lydia (Common Whitetail)
    • Ladona julia (White-fronted Corporal)
    • Sympetrum obtrusum (White-faced Meadowhawk)
    • Leucorrhinia intacta (Dot-tailed Whiteface)
    • Tramea lacerata (Black Saddlebags)
    • Tramea onusta (Red Saddlebags)
    • Erythemis simplicicolis (Eastern Pondhawk)
  • Damselflies (Zygoptera)
    • Calopteryx maculata (Ebony Jewelwing)
    • Lestes rectangularis (Slender Spreadwing)
    • Ishnura verticalis (Eastern Forktail)
    • Enallagma civile (Familiar Bluet)
    • E. cyathigerum (Northern Bluet)
    • E. ebrium (Marsh Bluet)
    • E. hageni (Hagen's Bluet)
    • E. signatum (Orange Bluet)
       

More information about dragonflies

 

 

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Last updated on May 9, 2014