People fall into two camps: those who like dragonflies,
and those who think they are creepy. My husband gets the willies when he sees
them, whereas I think they look like jewels flitting over the water. Regardless
of your feelings toward these lacy-winged creatures, be glad you weren't
roaming the earth 250 million years ago. Dragonfly fossils from the era have a wingspan of over two feet.
of various scientific denominations are also
commonly called darners, damselflies, clubtails and skimmers. For convenience,
I'm calling them all dragonflies! If you're interested in more detail about the
order Odonata (which means "toothed jaw"), see the reading list that
accompanies this story.
It's not necessary to know the order, family, genus and
species of each dragonfly. What is
most important for the water gardener to know about dragonflies is the
relationship that these insects have with the pond. Some pondkeepers believe
that dragonflies are pests; others are starting to view their symbiotic
relationship with water gardens as a beneficial one. One thing is for certain,
though. The presence of
dragonflies around your pond is an indication of the health and diversity of
your water garden's ecosystem.
The Invisible Dragonfly
reason you see dragonflies around bodies of water is
that they spend the majority of their lives as aquatic creatures. Their entire
life cycle, from egg to death, can last from one to over five years, depending
on the species. Dragonflies are on the wing for only a fraction of their lives.
lay their eggs in aquatic vegetation,
mud or in open water in ponds, lakes and rivers. Eggs hatch into nymphs, called
naiads, when conditions are right, usually within a few weeks or months. Like
other insects, dragonfly larvae spend their time feeding, molting their skin in
a series of "instars," preparing to become adults.
I've read some water gardening authors who describe
"hideousness" of dragonfly larvae. One author describes them as
"scorpion-like creatures" that wait in the mud for prey. They breathe
with gills, occasionally shooting out their claw-like lower jaw (called a
"mask") to impale a snack. Their large google-eyes are retained into
The advocates of the "dragonflies are pests"
theory have correctly observed one trait of dragonfly larvae: they will eat just about
is smaller than they are. Dragonfly larvae are predators of small fry and
tadpoles-those creatures that we want in our ponds. It can be heartbreaking to
find that most of your newly-hatched goldfish or koi have disappeared without a
To their credit, dragonfly larvae consume some pond
pests, too. They munch on mosquito larvae, leeches, bloodworms, snails and
other bugs. The dragonfly larvae are, in turn, eaten by adult fish, frogs, and
Eventually, dragonfly larvae metamorphize into adults.
The larvae crawl up on a reed or a stem and attach themselves firmly. Soon,
their hardened skin breaks open and the adult dragonfly struggles forth. Body
fluids are vigorously pumped throughout the insect's body, causing the body and
wing buds to expand. The wing buds then unfurl into the lacy wings that will
carry the dragonfly through adulthood.
To complete the life cycle, dragonflies head away from
the water. Within days, they have developed their full coloring and sexual
maturity. Like the larvae, adult dragonflies are voracious feeders. Here's
where they truly become an important beneficial insect. They consume large
quantities of flies, mosquitoes and other flying insect pests.
Dragonfly are--at worst--just a
part of the water garden's
food chain. If the pond ecosystem is out of balance, for example, with too many
dragonfly larvae, not enough plants, and few other insects, the larvae will
decimate young fish populations. It is important to maintain a good
balance of all they key players in the pond. The water gardener can encourage a
healthy pond ecosystem that supports all of the flora and fauna by not using pesticides
anywhere in the garden.