Showing posts with label Beneficial Insects. Show all posts
Showing posts with label Beneficial Insects. Show all posts

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"


Damselfly


Dragonfly

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!
Darren

Sunday, May 2, 2010

The TEST

One thing that all gardeners have in common is, the battle with insects. Your plants are doing great one day, then the next they have holes in the leaves, bites taken out of the fruit, or little critters just running all over them. What do most gardeners do? They reach for the insecticide and spray away. Now the question is, did you really need to spray? Was it a good bug or a bad bug? I understand that most gardeners know what an Aphid looks like or even a Mealybug. I am also pretty sure they know what a Ladybug looks like. What about a Ladybug larvae? Ever see anything like this on your plants?



These are all good guys and should not be sprayed.
I did a lecture back in March on Good Bugs, Bad Bugs and was surprised at the responses I got. I thought today would be a good day to repeat that experiment. I am going to show you a bunch of pictures of Good Bugs and Bad Bugs. Be honest with yourself, don't look to see what it is before you make a guess. There is not going to be any grades, and nobody else will know how you really did. It could, in the end, help your garden grow.

Let's get started:

GOOD BUG or BAD BUG?



GOOD...Red Soldier Beetle.... The larvae are carnivorous, feeding on insects in the soil. The adults are also predators, eating caterpillars, eggs, aphids, and other soft-bodied insects. Soldier beetles resemble lightning bugs but do not have light-producing organs.

GOOD BUG or BAD BUG?




BAD....Common Asparagus Beetle......Both the larvae and the adults of the Common Asparagus Beetle damage Asparagus plants. The overwintered adults emerge and begin to feed on the tender growing tips of the newly sprouted Asparagus.

GOOD BUG or BAD BUG?




BAD....Buffalo Treehopper....Both nymphs and adults suck sap for food. Plants include Willows, Elms, Cherry, Black Locust, Goldenrods, Asters as well as others.

How you doing so far?

GOOD BUG or BAD BUG?




GOOD.....Horned Assassin Bug.....This bug kills many garden pests including flies, mosquitoes, beetles and large caterpillars.

GOOD BUG or BAD BUG?




GOOD....Big Eyed Bug.....They are regarded as beneficial because they prey upon numerous kinds of insect and mite pests of turf, ornamental and agricultural crops.

One more.
GOOD BUG or BAD BUG?




BOTH....Earwig.....Earwigs are omnivorous, and will feed on dead plant material and dead or slow invertebrates. However, in large numbers, may feed on tender plants and may damage Lettuce, Strawberries, Dahlias, Marigolds, Zinnias and Roses. There are 22 types of Earwigs in the United States.
I hope this little test has given you an idea of the types of insects that there are in your garden. There is an estimated 900 thousand to over one million species of insects in the world, with more being discovered every year. There is a very handy item out there that you can get to help with some of the identifications. Do a Google search for "Mac's Field Guide of Insects". I use mine all the time. They are not very expensive. Besides, wouldn't it be a good idea to learn a little bit about the insects in your little corner of the world? Or at least be able to tell the difference between the good guys and the bad guys? I'm just sayin'!
Happy Growing!
Darren