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Tag Archive | "dragonflies"

Arrowhead Spiketail Life Cycle


By Ranger Steve Mueller

 

Flying rapidly close to the surface of shallow water in Little Cedar Creek headwaters, an Arrowhead Spiketail dragonfly guards a territory. Males fly back and forth over a section of stream protecting areas where water flows over a muck bottom. A female lays her eggs in the muck where water is shallow enough for her to reach her long abdomen into the soft bottom. She needs seeping springs that feed streams in forested habitat. 

The Arrowhead Spiketail has not been collected extensively in Michigan. It lives in eastern North America. The Michigan Odonata Survey documents distribution evidence with specimens in the University of Michigan research museum. Interestingly, no specimens are vouchered to document its presence for our area of the state. 

I have only noticed it when hiking in Porcupine Mountains State Park and at Ody Brook Nature Sanctuary. 

It is a beautiful dragonfly with a black abdomen and bright yellow arrowhead spots on the top of the abdomen.

Many species of dragonflies appear in abundance during summer. A walk through a field will provide a glimpse at fast-moving young adults. Many remain on the wing making it difficult to recognize identification details. They are busy removing flying insects. Thank them for making your walk more pleasant by eating insects that might eat part of you. Some dragonflies eat their weight in mosquitos in one hour. 

Young adults are often found far from water. When sexually ready to mate, they head to a species-specific water type of lake, pond, river, bog, swamp, stream, or seep where young develop. Each species experiences a similar development with variations that help it thrive in its specialized nature niche. 

The mating process for dragonflies is unique. Insects have three body parts–head, thorax, and abdomen. The male transfers sperm from the end of his abdomen to a pocket near the attachment of his abdomen and thorax. Using claspers at the end of his abdomen, the male grabs the female by the head. When the female is held firmly by the head, she bends her abdomen in a loop to where the sperm packet is stored. A penis in the pocket on the male scoops out any sperm packets or pushes them aside to ensure his sperm sires offspring. Some dragonflies stay attached while females lay eggs and some release them but fly nearby to keep other males away. I do not know spiketail methods for protecting females from being mated by other males. Does he stay attached or fly nearby?

Female dragonflies lay eggs in appropriate habitat. Some species skim the water surface dropping eggs that sink to the bottom. Others lay eggs in vegetation that drop into water when hatched. Some lay eggs on land that will be carried into water during flooding. Each species has different egg laying techniques. 

When the egg hatches, a small naiad begins its life feeding on other stream life. Some crawl on the stream bottom while others remain stationary and buried in bottom sediments waiting for food to drift to them. They are predators eating aquatic organisms. If found, the dragonfly becomes prey for fish and other organisms. 

To survive, they are camouflaged and remain hidden. Their gills are tucked inside their rear end so they suck oxygen rich water in their butt to pass over the gills. On the underside of the head is the deadly flat feeding structure that unfolds with great speed. At its end are pinchers that grab prey and the flap folds to bring the prey to chewing mouth parts where the food is dismembered and swallowed. Some naiad larvae develop into adults in one year while other species take many years.  

Dragonflies have three developmental stages; egg, naiad, and adult. They have incomplete metamorphosis as opposed to complete like butterflies that have egg, caterpillar, pupa, and adult. The naiad sheds its exoskeleton many times as it grows and finally when developed enough, it will climb from the water on vegetation where it emerges from its final naiad skeleton. It squeezes from the exoskeleton by arching backward from the shell-like covering. Its adult legs grasp the plant to hold tightly while it pumps fluid into expanding wings. When wings dry, it begins flight, feeds, and mates to complete the life cycle that begins a new generation of dragonflies.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

Posted in Outdoors, Ranger Steve's Nature NicheComments (0)


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