Dragonflies and Damselflies
Dragonflies and Damselflies
'Devil's darning needle', 'Mosquito hawk', 'snake doctor', are some of the more colorful local names that refer to these spectacular insects.
As a child, I would hear how dragonflies would sew your mouth shut and bite you.
They were an insect to leave alone.
Despite a widespread belief that they sting, they do not.
They have no means of stinging and are completely harmless to man.
In fact, studies indicate they are one of our most beneficial insects.
Dragonflies and Damselflies, a closely related group, belong to the order Odonata.
They have large compound eyes, short, bristle-like antennae, and four elongate membranous wings.
Some species have transparent, colorless or somber-hued wings; others have brilliantly colored ones blue, green, purple, white, or bronze.
Still others may have conspicuous mottling or spotting on the wings.
Not only the wings, but their bodies may be brightly colored as well.
Damselflies are easily distinguished in the field by their more delicate features and the vertical position of the wings over the abdomen when at rest.
Furthermore, the hind wing of the Damselfly is essentially similar to the fore wing, while the hind wing of the dragonfly broadens near the base, caudal to the connecting point at the body.
Damselflies are also usually smaller, weaker fliers than their larger cousins, and their eyes are separated.
Dragonflies are more robust in structure, strong fliers, and hold their wings in a horizontal position when resting.
They are master aerialists, capable of swift flight, of a backward as well as a forward darting movement, and of hovering
Of the approximately 5,000 species of Odonata in the world, over 360 species occur in the United States and Canada.
Present day Odonata in the United States range in wingspread from 1 1/4 inches(32mm) to almost 5 inches (127mm).
An extinct family member, Meganeura monyi, known only from fossil beds, had a wingspread of about 2 1/2 feet (762mm).
Now that is one big insect.
Mating logistics seem to me one of the more ridiculous contrivances in the animal kingdom.
They are unique in the insect world in that the male possess a set of secondary reproductive organs on the abdomen segments as well as his primary apparatus on the at the end of his abdomen.
Before mating can occur, the male must charge his secondary copulatory apparatus with sperm from his primary copulatory apparatus.
Mating commences with the male grasping the female with his abdominal claspers.
The pair then assume the wheel position with the tip of the females abdomen and thus her reproductive apparatus engaging the males secondary copulatory apparatus.
The male first uses his penis to remove any sperm left by a previous male before inseminating her himself.
Copulation can take from several minutes to several hours depending on species.
The male stays in tandem with the female in many species while she lays her eggs.
In those species which lay endophytically some lay below the water line, and in some cases both the male and the female may become fully submerged.
In other species the male stays close to the female guarding her while she lays.
In those strongly territorial species the may be satisfied by continuing to expel all other males from his territory.
This allows the female to lay within the territory at her leisure.
In early spring the eggs may be deposited in floating masses of plant debris (dragonfly eggs to your right).
The female green darner, unlike many other species, has an ovipositor that it uses to insert eggs into the stems of aquatic plants.
During the growing season it deposits yellowish, 1mm-long eggs into a double row of slits along a plant stem beneath the surface of the water.
(Pictured to your right.)
After about three weeks the young emerge and live underwater, voraciously feeding on small aquatic animals like tadpoles, little fish, mosquito larvae and just about anything it can get a hold of.
Many successive molts take place over a period of eleven months before the final nymphal stage is reached.
The mature dragonfly nymph crawls out of the water onto a rock or plant stem during the night or early morning hours.
The nymphal skin splits dorsally and the winged adult pulls itself out to become fully expanded in about half an hour.
However, it is several days before it reaches its peak flight capacity.
Dragonflies and Damselflies:
Predator and Prey:
These insects have excellent eyesight.
The large, hemispherical compound eyes are used in searching for small air-borne insects.
Each eye is composed of nearly 30,000 distinct sight elements called ommatidia.
Each of which is a separate light-sensing organ , arranged to give nearly a 360° field of vision.
The Insect positions its six legs in a basket-like manner literally to scoop its prey out of the air.
The two front legs hold the prey in position so that it may be eaten while in flight.
They in turn, may be food for swifts, swallows,
purple martins, kingbirds, frogs and other dragonflies.
It is usually attacked when it is basically immobile, during and shortly after transformation from the nymphal stage to the adult.
Although they tend to feed indiscriminately, as a group they serve an important ecological function in aquatic and aerial habitats.
The nymphs are an important part of the food chain from many species of fish and, eventually, for other top predators, including man.
Perhaps more important to man is the role of the adult in helping to check population levels of those insects such as mosquitoes (which transmit diseases such as Encephalitis, Malaria, Yellow Fever, Dengue, West Nile Virus and Dog Heartworm), and horse flies and deer flies, which transmit Anthrax and Tularemia.
They also help to control other biting flies such as black flies, sand flies, punkies (.no-see-ums.), midges, eye gnats, and stable flies.
Only one species the Bee butcher (Coryphaeschna ingens), is known to be an economic pest.
In the southeastern United States it feeds on honeybees as they fly to and from their hives.
Predator animals were once poorly understood and considered to be man's enemies because of their habit of preying.
Scientists have shown they are necessary for abiological equilibrium.
Damselflies and Dragonflies are not the complete answer to controlling certain kinds of insect pests.
They are one of God's many sources to help reduce the population levels and to become food for other living creatures.
A small part of Nature's life cycle.
Dragonflies have also been used as indicator species for assessing habitat and water quality in a variety of wetlands, riparian forests, and lake shore habitats around the world.
Friend or Foe?
The choice is clear.
Dragonflies and Other Beneficial Insects
Build a Beneficial Insectary
Water Gardens to Attract
Build a Wildlife Habitat
Insects are a part of God's delicate balance.
Yes, we need them in 'Gardening For Wildlife'.