Introduction to Dragonflies
Dragonflies are a part of the order of Odonata. They have 2 pairs of transparent wings and a very elongated body. They are abundant near Missouri’s massive systems of slow moving bodies of water. Dragonflies in their larval stages live in ponds and rivers, consuming other harmful pests’ larvaes in the water. The males will usually fly in circle among the edges of lakes in order to show their dominance of a certain body of water.
Dragonflies have three major body parts: the head, thorax, and abdomen. Dragonflies rely on their heads for sight and consumption, their thorax for powering their two pairs of wings, and their abdomen for mating and reproducing offsprings.
Dragonflies have huge eyes and narrow necks which allow them to have a very flexible and wide view on the surroundings. Besides their huge eyes, their frons, postclypeus, anteclypeus, and labrum make up the rest of faces. They are able to move their heads independently because of their Prothoraxes, which are attached to their first pair of legs. The Prothoraxes are connected to the heads and act like necks for the dragonflies. Dragonflies also have three tiny eyes on top of their heads, called Ocelli. Those three little eyes are arranged in a triangle located directly between the two giant eyes. The ocelli are used by dragonflies to detect light intensity. On the sides of the Ocelli, there are two antennae sticking out. Dragonflies do not use their antennae to smell like most of the other insect species but instead they use them to detect wind speed. (Paulson, 2011)
One of the most important part of the dragonflies is their thorax. They are important because they have all the powerful muscles to drive dragonflies’s large wings. Also there located sets of muscles to move the legs. The thorax is also very important for insect identification because on most of the dragonflies species there are patterns on the thorax to identify. (Paulson, 2011)
Dragonflies’s abdomens are made of 10 segments. they contain digestive tract and sexual orgams. Dragonflies have relatively long abdomens compared to other insects, and that is because the long tail could be more aerodynamic. Also the long tails help to counter balance the heavy weight of the big wings to make the flights more maneuverable. Female dragonflies have a wider abdomen because they need more rooms to carry eggs. In the last segments of the dragonflies’s abdomens locate the cerci of both species. One could also identify the sex of the dragonflies by looking at their abdomens. The females have reproductive tract opens at S8 and S9 on their abdomens. (Paulson, 2011)
Dragonflies have two sets of wings. One set of forewings and one set of hindwings. Dragonflies have a set of much larger and broader hindwings. All dragonfly species have a distinct set of markers on their wings. Dragonflies have Pterostigmas on the tip of their wings. Pterostigmas are hardened and heavier pieces of wing compared to the rest of the wing. Dragonflies have those to reduce vibrations in flight so they can fly more smoothly and easily. (Paulson, 2011)
Most of the dragonflies are various shades of black, brown, red, and yellow. The blues on a dragonfly are usually caused by their internal structures. Greens are made with yellow pigments on blue structural colors. Metalic colors are also structural, such as eyes. As dragonflies mature they become truer to their colors. When dragonflies mature, they will have a dramastic change in their colors. Dragonfly species in a same family or genus may have similar color patternings on their abdomens and thorax. (Paulson, 2011)
Common Dragonflies in Missouri
Eastern Pondhawk (Erythemis simplicicollis)
It is medium in size. Male has blue green eyes and female has olive brown eyes. Male has a pale blue body, while the female has bright green abdomen and thorax. The immature males are at first bright in color then gets duller as they matures and ages. The species is abundant and favored wetlands. It is also one of the very few dragonfly species that favors grand perching. It is a very voracious species because it, especially the female, eats a huge number of other odonates per day. (Dragonflies of Missouri) (Paulson, 2011)
Familiar Bluet (Enallagma civile)
This dragonfly species is extremely abundant in Missouri but very local. Male has blue eyes and small black caps. It has bluet stripes on its thorax. Male has large blue middle segments. It has a black spot on the second segment on its abdomen. Females are polymorphic and can vary between blue or brown. Females have tan to greenish eyes with brown cap. The distinguishing factor is that females’ abdomen has black covering along all segments, with typical bluet torpedo pattern evident. It has a mating peak during the midday and has very lengthy mating flights. (Paulson, 2011)
Great Blue Skimmer (Libellula vibrans)
It is a very large dragonfly. It is a skimmer and is white in the front of its head. Male has bright blue eyes. Its therox and abdomen are entirely blue without stripes or patterns. The color of female dragonfly becomes duller as it ages. Male defends small territories over water bodies in woodlands. Female likes to tap water repeatly to drop eggs in an area. (Paulson, 2011)
Black Saddlebags Skimmer (Tramea lacerata)
Black Saddle bags Skimmer is a typer of skimmer dragonfly. Its body is shorter than its wing span. It has black spots on its wings. It migrates to warmer areas in the fall. It likes to fly in swams with other dragonflies for protection and preying. It is very easy to identiy because of the partially black colored hindwing. (Dragonflies of Missouri)
Blue Dasher (Pachydiplax longipennis)
It is one of the most abundant species of dragonflies in the United States. It likes to swim around lakes and rivers. Its eyes have metalic colors. The female has yellow stripes on the sides and top of its abdomen. It has a relatively blue abdomen and a very blue abdomen tip ending. (Dragonflies of Missouri)
Blue-fronted dancer(Argia apicalis)
This dragonfly is widespread in the United States. It has an unpatterned thorax. Its head is blue at the top and the front. Male has almost an entirely blue colored thorax and abdomen tip. It has a vividly striped blue abdomen tip. It has partially developed black humeral stripes. Male usually flies at a six feet interval above lakes for about three hours. It lives in various habitates such as rivers and streams. It prefers actively running water than lakes and ponds. (Paulson, 2011)
Common Green Darner (Anax junius)
This dragonfly is large in size. It has an almost all green thorax and that is very noticable. Its wings are transparent. One can identify a common green darner with ease because it has an eye spot on the top of its head. it is usually found near water sources. Female will not splash or drop the egg but rather gently dip its abdomen in the water and lay one egg at a time. (Paulson, 2011)
Common Sanddragon (Progomphus obscurus)
This dragonfly prefers moving bodies of water. It has a very identifiable color configuation on its body. It has dark yellow eyes and dark yellow face. Its thorax is patterned with yellow and black stripes. Its abdomen is also color with black and yellow stripes. Its wings are highlighted with yellow color. Female will drop eggs into the water alone without the male. (Paulson, 2011)
Common Whitetail Skimmer (Libellula lydia)
This dragonfly is very unique because it has a flat abdomen. It has a white chalky abdomen. It uses its whitle and flat tail to flash signals to other dragonflies to warn them out of the territory. They live near ponds and water sources. It is very easy to identify common whitetail skimmers because of their unique white flat abdomens. (Paulson, 2011)
Eastern Amberwing (Perithemis tenera)
It is tiny in size. It has orange wings and legs. Most of its body is also orange colored. There are multiple orange triangles in its middle abdomen. One of its distinctive feature is it has orange veins on its wings. It is very easy to identify since there is no other similar species of dragonfly in its area. (Paulson, 2011)
Slaty Skimmer (Libellula incesta)
It is large in size. It has dark legs and a dark face. Male has dark brown eyes and a metalic blue face. It is really easy to be identified because from far it is the only all black large dragonfly species in the area. Female drops eggs into vegetations and waters with male flying near her for protection. (Paulson, 2011)
Widow Skimmer (Libellula luctuosa)
It is large in size. It is really obvious from far because it has dark shaded wing bases. Male has white shades on its wings outside its black shades. It has a very distinctively colored wings for identification. It is common in meadows and roadsides. It also appears often in the areas far away from a water source. It likes to defend a large area of mating territory and the winner gets the chance to mate. (Paulson, 2011)
Hine’s Emerald (Somatochlora hineana)
This midwestern emerald lives in very restricted ranges. It has a unique striped thorax. Male has a dull yellow or brown face and a metallic green or brown thorax. Its abdomen is black with yellow spots on the second segment. Female has a similar color pattern although its abdomen might vary. To dinstingush it from other smiliar species, one need to notice that the Hine’s emerald has a straight cerci. This species is endangered right now. It is typically seen in clearings in woodland. Males tend to fly slowly over their territories and mate with the females trespassing their territories. Its habitats are wetlands and meadows with shallow water. (Paulson, 2011)
Dragonflies and all odonates are aquatic insects, so the best place to find them is near various bodies of water. Warm lake with many vegetations could have more species and population than a cold pond with a few plants. Many dragonfly species are specialist and they demand specific habitats. Also, many dragonfly species would only be abundant in specific seasons and specfic times of a day, so really do your research before trying to find your dragonflies. Free free bodies of water could be excellent habitat for dragonflies. (Paulson, 2011)
Although seems crude, the best way to identify a dragonfly is to catch it. Many dragonflies could be identified easily in the field, but there are also many dragonflies that you only could identify in your hand. It is the best to catch adult dragonflies since they possibiliy alreay mated and are more sturdy to handle with. The just emerged dragonflies are extremely fragile to handle and could be easily damaged. Dragonflies in North America are pretty abundand and catching a few specimens wouldn’t endanger any species, but keep in mind that in most of the parks you would need a permit to catch dragonflies for research and education. (Paulson, 2011)
There are six steps for collecting a dragonfly for specimen.
1. Catch it
Dragonflies are hard to catch because they have predators like birds. They have quick response times and are able to fly away rather quickly. It is the best to wait for a dragonfly to stay still on vegetations and sweep side ways. If the dragonfly is in heavy vegetation, then you should sweep the net from above. When the dragonfly is in the net, you would need to lift the end of the net up so the dragonfly will fly into the end of the net. When caught in net, dragonflies tend to fly straight upwards and usually when collector opens the net to catch the dragonflies they fly straight out. When the dragonflies are in flight, try to sweep the net from behind or below, as dragonflies have poor visions in these directions. You should flip the net over as soon as the dragonfly is in the net to prevent it from escaping. It is usually safe to handle dragonflies by bare hands, but beware some of the larger species as they would make you “ouch!”.
2. Envelope it
Place the caught dragonflies in a glassine envelope with their wings folded back. If you are putting two or more dragonflies in a same envelope you should place them in opposite direction as they might chew on each other. Everything should be labeled.
3. Acetone it
Kill the dragonflies by dropping acetone on to their thorax or simply submerge them in acetone. After that, you would need to straightened their abdomens and organize them so they dont cover up other body parts. Make sure the wings are also separated. Leave them submerged in acetone for 12 to 24 hours and the acetone could get rid of any water or fat in the dragonflies’s body. As a result, acetone treated specimen have much better color preservation.
4. Remove it
Remove the dragonflies from acetone and let them dry for one day in the fresh air so the acetone liquid could evaporate. Acetoned dragonflies are more sturdy and tougher to be damaged compared to the traditionally dried dragonfly specimen.
5. Label it
All the dragonflies should have the following informations labeled. Locality, date, collector. Latitude and longitude could also be added. Habitat notes should also be included.
6. Store it
Store all the acetoned or dried dragonfly specimens in dry places. Aviod humidity at all cost. Also you need to beware of pests and other insects from eating and damaging your dragonflies.
Researches on Dragonfly
Humans have affected dragonflies in multiple ways and many influences are surprisingly positive. Take the man-made water bodies for example that have become an ideal breeding ground for dragonfly species. One research was done to determine the richness of dragonfly species in man-made ponds. The researchers discovered that as the man-made pond ages and becomes richer with vegetation, more dragonfly species appeared in the pond. The size of a pond also has a positive correlation with the amount of dragonfly species present. The adult dragonflies chose habitats based on the type and amount of vegetation present in a pond which is significantly abundant in the newly established human induced water bodies. As more aquatic vegetation develops in the water body, more species of dragonflies would come to breed. Flyer species of the dragonflies are usually only seen in large ponds. The relationship between dragonflies and humans is very important because what people do might greatly impact the dragonflies. Dragonflies are also useful insects because they consume a countless number of pests per day, which is both beneficial to the environment and our human industries. (KADOYA, T., SUDA, S.-i. and WASHITANI, I. 2004)
Human could also use dragonflies as an indicator of changes in the ecosystem. Dragonflies are part of the standard biomonitoring surveys in many parts of the world. People could use dragonflies to indicate climate change and its effects in certain areas directly. The researchers discovered dragonflies is highly sensitive to enviormental changes and making them great samples to study freshwater ecosystems and climate change. This could be important for global warming research and it could add up to the evidence of an impending global crisis. (Bush, A., Theischinger, G., Nipperess, D., Turak, E. and Hughes, L, 2013)
There are also studies on dragonflies’s flying method to explore how dragonflies utlize minimun amount of energy to keep its rather large and heavy body speedy and agile in the air. The front flaps of wing could move separately with the back set of the wings when it is needed. When dragonflies take off, they flap both sets of wings to gain the maxium air lift in a burst. However, when the dragonflies are in the air hovering, they alternate the flapping motion with their two sets of wings to generate a continuous flow of air lift. This is interesting because it can inspire new types flying machines which might use less energy in flight. (American Physical Society, 2007)
Note the wing positionings of the dragonfly
The wings of the dragonflies are also special. Both pairs have many veins and those veins give the wings of dragonfly an antifatigue property. While making the wings both thin and light to be useful in flight, the veins are able to make the wings able to bear a surprising amount of alternating stress when flapping up and down in flight. The crossveins dividing the wings into small blocks could stop breakages and make the wings have a strong tensile strength. (Li, X.-J., Zhang, Z.-H., Liang, Y.-H., Ren, L.-Q., Jie, M. and Yang, Z.-G, 2014)
A study was done in the Johnson Shut-ins state park to determines the population of an endangered species of dragonfly, Hine’s Emerald. Hine’s Emerald has narrow habitatual requirements thus is not very populated but refined to small wetland patches. However, Missouri has some sites that meets Hine’s Emerald’s requirement. Previous observations have failed to calculated a reliable population number, so this time a Mark-Recapture study was done. In conclusion, it is calculated there is an estimate of 176 Hine’s Emerald dragonflies in this state park area. (Walker, J. & Smentowski J, 2014)
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Emerald Dragonfly ( Somatochlora hineana Williamson) at Johnson Shut-ins State Park, Missouri. Cape Girardeau, Missouri Department of Conservation.
This page was written and created by Taili Zhuang