Saturday, August 6, 2011

Damsels and Dragons

You read all the time about attracting beneficial insects to your garden. This list may include such things at Ladybugs, Assassin Bugs, Bees and so on. There are a couple of beneficials that come around every year that I just love to watch. I often wonder just how many insects I would have if it weren't for these friends,they are the Damsels and Dragons of the yard....better known as Damselflies and Dragonflies.
Both of these creatures belong to the order Odonata, which translated means "Toothed Ones"



Currently about 5000 species of Dragonflies and Damselflies are known; experts guess that there are probably between 5500 and 6500 species in total.
While both Dragonflies and Damselflies belong to the same group, there are many noticeable differences.
We will start with their eyes. They both have very large compound eyes relative to the rest of their body. Each compound eye is composed of nearly 28,000 individual units. More than 80% of their brain is devoted to analyzing visual information. The Dragonflies have eyes that touch, or nearly touch, at the top of the head. The Damselflies eyes are clearly separated, usually appearing on each side of the head.
While it might be a little difficult to tell the difference in their eyes, their bodies are pretty much a dead giveaway. The Dragonfly body is usually very stocky. We have one here that kind of looks like a flying marijuana cigarette, unfortunately I have not been able to snap a picture of it. The Damselfly on the other hand, is very slender and fragile looking. You can see this in the pictures above.
When they are resting, they hold their wings differently. Again, as you can see in the pictures above, the Dragonfly hold its wings out open, while the Damselfly holds them closed above the body.
Dragonflies are some of the fastest insects in the world. They can fly forward at about 100 body lengths per second,to put that in terms we can relate to, about 38 MPH. They can also fly backwards at about 3 body lengths per second, plus are capable of hovering in the air for sixty seconds or so. Damselflies are much weaker fliers in comparison.
The odonata order are known to be among the oldest of insects. The oldest recognizable fossils of the group are 325 million years old. They must be doing something right to be hanging around for that long.
I enjoy having them around because, one, they are fun to watch fly around and two, because they are valuable predators that eat mosquitoes, and other small insects like flies, bees, ants, and on the rare occasion, butterflies. A grown dragonfly can eat more than 50 mosquitoes a day or it can eat food equal to its own weight in about 30 minutes. Think about how much food you would have to eat at that rate?!
Here are some more scary facts, today's Damsels and Dragons have an average wingspan of just under 2 to just over 3 inches. There are fossils belonging to some species of these carnivorous insects with wings spreading to spans in the range of two and a half feet and made their food out of other insects and even small amphibians. If some of these were alive today, I have visions of my Chihuahua being carried away by some big old Dragonfly as lunch!
Most of a Dragonflies life is spent in the larval stage where it molts from six to fifteen times. Depending on altitude and latitude, larval development varies from the common one or two years to as many as six years. At that time, the nymph crawls up out of the water and molts one last time, emerging from its old skin as an adult with functional wings. After this final molt, the life span is anywhere from one month to six months, depending on the species.
Both Damsels and Dragons start their life in water, therefore they are often found near water: ponds, lakes, canals, streams, rivers and swamps. They are found on every continent except for Antarctica.
As beneficial as these things are, they have gotten a bum wrap in some cultures.
In Europe, Dragonflies have often been seen as sinister. Some English vernacular names, such as "devil's darning needle" and "ear cutter", link them with evil or injury.
The Norwegian name for Dragonflies is "Øyenstikker", which literally means Eye Poker and in Portugal they are sometimes called "Tira-olhos" meaning, Eye snatcher.
I must admit, I had not heard this one: In the Southern United States the term "snake doctor" refers to a folk belief that Dragonflies follow snakes around and stitch them back together if they are injured.
There are other interesting things associated with them. For some Native American tribes they represent swiftness and activity, and for the Navajo they symbolize pure water. The part about the water makes sense, Dragonflies are fairly sensitive to pollution.
In some parts of the world they are a food source, eaten either as adults or larvae; in Indonesia, for example, they are caught on poles made sticky with birdlime,(a sticky substance made from the bark of a holly bush, usually Ilex aquifolium) then fried in oil as a delicacy.
I was asked this question one day, do Dragonflies or Damselflies bite? No, though large dragonflies will sometimes try to bite, they fail to break the skin.
I don't recommend this one, but, Japanese children catch large Dragonflies as a game, using a hair with a small pebble tied to each end, which they throw into the air. The Dragonfly mistakes the pebbles for prey, gets tangled in the hair, and is dragged to the ground by the weight. I guess its better than running the streets or playing X-Box all day!
I will leave you today with a look at some of the beautiful colors that these creatures come in. I urge you to go out into the field or even your backyard and look for your own Damsels and Dragons. You might also want to thank them for the hard work they do eating all of those nasty bugs!

Happy Growing!

1 comment:

  1. I love these guys around the garden....although since our pool is gone now, we don't have many fluttering around.