Read about Kathy Biggs

 

 

They are far more than "jewelry" for your pond!


Flame skimmer
© Dave Biggs

Dragonflies
at the Water Garden

by Kathy Biggs
California, USA
Click images to enlarge

You’ve undoubtedly noticed dragonflies and their aerial antics above your pond or water feature. Perhaps you’ve even noticed them dipping into your pond. And I hope you consider them a welcome bonus, because they are!

Dragonflies and damselflies are members of the insect order Odonata. These four-winged wonders spend their hectic adult lives as flying predators, not nectar sippers like the butterflies. As predators they eat mosquitoes, flies and other small flying insects. But did you know that they are even more ferocious predators in their underwater juvenile state as nymph? It’s true! Let’s learn more about these dramatic entertainers, as they are so much more than just pretty “jewelry” for the water garden, performing many functions both in and above the pond.


By supplying a pond, large or small, you are providing the very habitat dragonflies need to breed, as they all lay their eggs into water, or next to water where rainfall will wash them into their necessary element. Even at the start of their lives as eggs, which either hatch within a week or two, or over-winter in the pond, dragonflies are vulnerable and need our protection. Many waterways have been drained, thus depleting the very environment necessary for their success here on earth. And many people clean their ponds of all debris, thereby unknowingly destroying the winter resting place of these inhabitants who provide so many services for us. 


Blue dasher - © Ray Bruun
Dragonflies have two main modes of egg laying: some splash dozens of their eggs at a time directly into a waterway or onto plant matter in a waterway, while others actually land on vegetation that is emerging from, or floating on, the water, and carefully place eggs, one or two at a time, into little slits they cut into the plant matter. Most dragonfly eggs are small, not much larger than the period at the end of this sentence. The eggs hatch within a few weeks and the tiny creatures that pop out are called nymph.

The dragonfly nymph look much like little dragons and it is assumed that’s how they got their name. Damselfly nymph are smaller, with three feathery gills at the end of their abdomen. Both are predators, starting out eating microscopic prey and as they grow larger, shedding their exoskeletons so that they can consume larger prey. Nymph usually go through about twelve “instar” states before becoming mature. As nymph they eat the larva of mosquitoes, black flies and other creatures harmful to mankind. By the time they reach their final stage of development before metamorphosing into flying insects, they may eat critters even a bit larger than themselves, which could include small fish and pollywogs.     

After about a year or more in northern climes, a nymph is mature and ready to become a flying adult. It looks about for a suitable place for this transformation, usually an emergent stem or rock, but sometimes the shoreline. It crawls up out of the water and hooks tiny claws at the end of its legs (tarsi) into the surface. Then it puffs itself up with air, thus cracking its exoskeleton over the area of its eyes and thorax. Then it pulls its head, thorax and legs out from this shell and spends about a half hour hanging limply while it awaits the hardening of its legs. It is totally helpless at this stage and birds find them delectable! 


Emerging cardinal meadowhawk
© Kathy Biggs
Once the legs have hardened the teneral dragonfly (think of it as “tentative” at this point!) lurches forward and grabs onto its exoskeleton, now referred to as an exuvia, and begins to puff up not only its wings, but also its body and even its eyes! At this point it finally spreads its wings and then flies away from the waterway to mature for a few days to a week or more, depending on its size, species and weather. 

The mature dragonfly will often return to the very habitat you have so thoughtfully provided for it. The male will claim a territory while awaiting a female. While there you’ll see him swooping about, catching critters on the wing, nipping off their wings (which if you watch closely you may see them fall back to the ground/water) and eating them. In this manner he performs a wonderful service for you and for our environment, greatly reducing the number of flying pests, while also entertaining us with its antics. 
 


Cardinal meadowhawks
© Kathy Biggs
Once the female shows up, the male will court her by grabbing her behind the eyeballs using the appendages at the end of his abdomen (these are NOT stingers!) and towing her to a suitable location where they, if she is willing, will assume the unique dragonfly mating wheel. Dragonfly mating can be quick, or quite prolonged. And what is very amazing is that in the case of a prolonged mating the male is not spending the whole time performing insemination.


 Cardinal meadowhawk
© Ray Bruun

He actually has several tools in a special bump under his second abdominal segment. One is for insemination, but he has another tool. This one is for “dissemination.” He uses this tool to scrape or pump out any sperm left inside the female from any prior mating she may have had. In this way he guarantees that his sperm fertilize her eggs when she taps them onto the water.

There are about 5,000 named dragonfly species in the world. Some specialize in the slow waters of ponds and lakes, while others use the faster waters of streams and rivers. By providing these habitats as water gardeners we benefit the Odonates (dragonflies and damselflies) and they, in turn, benefit the environment as flying predators, a “green” way to control pests.  


Kathy Biggs has been a wildlife ponder for twelve years. She has ponds in Sebastopol and McCloud, California, and it was the development of these ponds that led to her becoming a dragonfly enthusiast and expert. Read about her and her dragonfly books here --

Profile - Kathy Biggs

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