Dragonflies
As insects, the Odonata go through an amazing morphological change during their life cycle. Witnessing this metamorphosis is to observe one of the true wonders of our natural world. For a considerable part of their lives these organisms are totally aquatic, dependant on water for their survival. The remainder of their life is spent fully airborne and dependent on flight for survival. The transition is very impressive. This section is a brief introduction to this fascinating phenomenon.
Oviposition varies according to species and/or circumstance. Sometimes the male will guard the female to ensure the eggs he fertilized are deposited. This may even extend to remaining in tandem through the egg laying process. Egg laying with the male in tandem may be above the waterline, at the waterline or even below the waterline — sometimes so deep the male and female both plunge below the surface breathing air that is trapped in the fine hairs on their bodies. The eggs are deposited individually on suitable vegetation — from wood to reeds. If the eggs are deposited above the waterline, the newly emerged larvae may fall into the water, or the vegetation may become inundated with water by flood or by dropping that part of the limb once dead. Eggs may be deposited in the stream sediment by some species. In many cases when the insects are not paired during oviposition, the female hovers over a suitable location descending occasionally to dip her abdomen in the water and wash off an egg. Some species scatter their eggs over the water from the air. There have been occasions when females selected unsuitable surfaces to lay their eggs, including oil slicks, vehicles, etc. Odonate’s eggs vary in size, shape and color. Size and shape of the eggs is directly related to whether the eggs are deposited in plant material or not. Most eggs are less than one mm (0.04 inches) across and spherical or cylindrical. They may be yellow, orange, brown or green. The time spent in the ova is species and temperature dependant, generally ranging from one to eight weeks. Some species overwinter as eggs in which case the development is suspended temporarily, continuing in the spring.
Odonate larvae are called naiads. These aquatic predators feed on numerous aquatic insects including both mosquito larvae and other naiads, and even fish fry. In turn, they are prey for a wide variety of fish and frogs, even being used by trout fishermen as bait. Unlike the more familiar butterflies or moths, Odonata do not go through a pupal stage in their development.
The maturing odonates now spend some time away from the water maturing sexually. This period may last from days to weeks, depending on the species and environment.
The diets of Odonata are diverse, consisting mainly of other insects including gnats, mosquitoes, black flies, house flies, deer flies and even other odonates. This makes them quite popular with humans, especially hikers who welcome the presence of a dragonfly when swarmed by mosquitoes. Most species average one generation per year, overwintering as an egg or naiad and emerging in the spring.
Many skimmers fold their forelegs behind their heads and do not use them to hold a perch except in very windy conditions. Other skimmers like to rest the sides of one or more legs against a perch and not use the claws to hang on.
These insects are most active when temperatures are above 65 degrees Fahrenheit. Being poikilothermic creatures, odonates are dependant on environmental factors to regulate their body temperature. Because of this, the same dragonfly may perch in the open on the river bank in the early morning, perch on sticks in partial shade during the late morning, and perch in the shade during the heat of the afternoon.
When searching for dragonflies or damselflies, look for as many different aquatic habitats as possible. Check each available microhabitat. The downwind side of a pond may be particularly good on a windy day, especially for finding mating pairs! Look for rarer stream species in large, long established parks, forested watersheds and larger streams near the entry of unpolluted waterways. These areas of limited disturbance provide optimum nurseries for stream species
Watching Dragonflies
Viewing dragonflies can be done with the naked eye, but I would strongly recommend a pair of close focusing binoculars to make the job easier. Many species can be identified in the wild, but some troublesome species cannot be told apart without in-hand inspection. Some observers choose to catch these and examine them closely. Others choose to enjoy them without putting a name on them.
Dragonflies can be seen perched, either for long or short periods of time. Most perch close to water, hanging on twigs or floating vegetation, or flat on the ground or rocks. Others will soar to great heights or patrol rapidly over the water and are almost impossible to observe. Each species tends to have its own unique set of behaviors.
Some odes are more easily startled than others. Dragonflies are very aware of movement, as anyone who has tried to catch one can tell you. They have the ability to see in many directions at the same time due to their large compound eyes. But their ability to see behind them is limited. So, if you need to approach one, my best advice to you is to approach from the rear.
Your quiet presence will usually not disturb the dragonfly's normal behavior. Take a seat and give them some time to settle back into their normal routine. But be ready if one lands on you or next to you, you'll never get a better look.
The Lake side , Hill and
