Dancers, Darners, Skimmers, Clubtails, Forktails, Emeralds, Bluets, Spreadwings and Jewelwings! These are some of the colorful names given to families of insects in the order Odonata, which are commonly known as dragonflies and damselflies. Worldwide, there are over 5000 species of Odonata, and these beautiful, charismatic, and easily observed insects are denizens of ponds, lakes, rivers and other wetlands on every continent besides Antarctica.
Dragonflies (suborder Anisoptera) are most often larger than damselflies, and usually boldly patterned. Their four wings are each controlled by individual musculature, which gives them remarkable flight abilities. They have the ability to fly forward and backward, hover, and change direction on a dime. This gives them the distinction of being the most efficient hunters in the animal kingdom, with kill rates above 90% (some say close to 95%). This is especially remarkable when comparing them to larger mammals and sharks, whose kill rates may be only half of a dragonfly’s. Damselflies (suborder Zygoptera), on the other hand, are smaller and more delicate, and their hunting behavior is more subtle than that of a dragonfly. Where dragonflies often hunt on the wing, damselflies resort to gleaning smaller insects from perches, usually while nestled within vegetation. One noteworthy fact about damselflies, they can be cannibalistic, and we have seen damselflies eating damselflies of the same species.
Here in Mercer County, we have approximately 71 species of Odonata, according to the website njodes.org. Because Mercer County straddles two different geological regions, and because all habitat types are not present in all areas, it is not surprising that these species are not all distributed evenly throughout our county. However, some areas can provide great results for anyone interested in pursuing them.
For the past two summers, my sons and I have been taking a volunteer inventory of the Odonata at the Abbott Marshlands (“the marsh”) in Mercer and Burlington Counties. There was no structured sampling, just going out with a net, magnifying boxes, binoculars and camera and capturing dragonflies on beautiful summer days. The results have been surprising in both the species richness (diversity) of dragonflies and damselflies present at the marsh, and also the sheer number of some of the individuals that we saw. In all, we found 38 unique and beautiful Odonata species in our travels in 2021 and 2022, and I’m confident that we’ll find at least a few more in our future searches. In the spaces below, I’m sharing some facts and photos about a few of the interesting species found at the marsh.
Blue Dasher
The Blue Dasher (Pachydiplax longipennis) is one of the most common dragonflies seen at the marsh, and is one of the most well-known dragonflies among amateur enthusiasts. This species exhibits a characteristic called sexual dichromatism, where the males and females are a different color. The more familiar males are blue with green eyes and an amber wash at the base of the wings, where the equally beautiful females (pictured here) are a sleek black and yellow. Immatures of both sexes have coloration like that of mature females. Look for massive emergences of these dragonflies at the western edge of Spring Lake in mid-July. If you see this, and you hold a stick high in the air, a blue dasher may perch on it for you!
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Common Whitetail
The Common Whitetail (Plathemis lydia) is a beautiful, widespread and frequently seen dragonfly whose range extends throughout New Jersey. Males (pictured here) have the bright white tails that give this species their common name, while the females are a drab brown and have different wing patterns. It is worthwhile to study these as a beginner, as the females may be mistaken for another less-common dragonfly (the Twelve-Spotted Skimmer (Libellula pulchella). In early to mid-June, look for very large emergences of Common Whitetails along the trails on the Island portion of Roebling Memorial Park. They are sometimes so numerous that they may land on you to bask. Don’t worry, they don’t bite or sting, so enjoy the experience!
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Georgia River Cruiser
The Georgia River Cruiser (Macromia illinoiensis georgina) was only seen once during the inventory that was performed during the 2022 season. Dragonflies may be categorized as perchers or fliers because of their behavior, and perchers are much more of a delight for newer Odonata enthusiasts because they will hold still for viewing and photos. Fliers fly relentlessly, and the Georgia River Cruiser can be solidly regarded as a flier! One cool and cloudy morning I had the fortune of finding this Georgia River Cruiser hanging on vegetation within the forest at Bordentown Bluffs, allowing me to capture this photograph of it.
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Russet-Tipped Clubtail
The Russet-Tipped Clubtail (Stylurus plagiatus) is an uncommon dragonfly that has a scattered distribution within the state of New Jersey. Its population status is unknown, and the website NJOdes.org lists this as imperiled in New Jersey, although this website has not been updated for several years. Anecdotal (but reliable) observations of this species illustrate healthy populations in some areas. There are several recent historical records of this species at the Abbott Marsh, including two specimens seen at Bordentown Bluffs in late summer of 2022. One of those specimens is pictured above. Note the club at the end of the tail that gives dragonflies in the Clubtail family (Gomphidae) their name, as well as the beautiful copper coloration of the Russet Tipped Clubtail, a striking contrast against the black and gold bodies and greenish eyes common among this family.
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Blue-Fronted Dancer
The Blue-Fronted Dancer (Argia apicalis) is named for its all-blue thorax. This damselfly is less commonly seen than the Fragile Forktail or Big Bluet, but is still relatively common along tidal creeks at the Abbott Marshlands. Dancers are named for their flight pattern, which is slightly bouncy. When perched, dancers usually have their wings folded slightly up and behind, and they often perch on bare ground instead of vegetation like most other damselflies. Look for them in August at the boat launch at Watson’s Creek.
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Fragile Forktail
The Fragile Forktail (Ischnura posita) is a very common damselfly at the Abbott Marsh, especially around Spring Lake at Roebling Memorial Park. This tiny damselfly is most easily identified by the ‘exclamation points’ on its thorax. To find one, you may have to look closely atop the plants around the lake, as it often hunts by gleaning insects while nestled within vegetation. The position that the pictured specimens are in is called the mating wheel, which is the position where the female receives the sperm from the male. If you see a pair of dragonflies or damselflies where the male is grasping the female behind her head with the appendage on his tail (and they are in a straight line), this is called a tandem pair, and is the precursor to the mating position.
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Eastern Amberwing
The Eastern Amberwing (Perithemis tenera) is a small, widespread dragonfly that is commonly seen perched on emergent vegetation over ponds and lakes throughout New Jersey. Because of their appearance, and how they wiggle their tails, these dragonflies are considered wasp mimics. This is an example of Batesian mimicry, a phenomenon where harmless species mimic dangerous ones to avoid predation. Note how the abdomen is raised at an angle in this picture? This is called obelisking, which is a strategy to keep the dragonfly cool on very hot days by reducing the surface area exposed to sunlight (note that the Blue Dasher in the photo gallery is also obelisking). Dragonflies will bask to warm themselves, and obelisk or sometimes even dip themselves in water to cool off.
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Big Bluet
The Big Bluet (Enallagma durum) is one of the most common and widespread damselflies at the Abbott Marshlands. This species is most common along tidal creeks such as Watson’s Creek, however they are also sometimes seen along Spring Lake and at field edges (especially immature specimens). True to their name, this species is slightly larger than most bluets and will sometimes capture other damselflies. I had the opportunity to photograph an adult Big Bluet cannibalizing an immature one at Watson’s Creek. This species is most common in late summer.
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Needham's Skimmer
The Needham’s Skimmer (Libellula needhami) is a large, beautiful skimmer that is common at coastal salt marshes and brackish water areas in New Jersey. In June of 2022, this specimen was captured along the power line cut at Roebling Memorial Park, and later in the season, a mature male (which is all red in color) was seen patrolling along the tidal creek off the eastern side of the lake. This is the first known occurrence of this species in Mercer County. Note that the tidal creeks at the Abbott Marsh have very low salinity, so it was a surprise to see this species here, and it is an exciting addition to the list of Odonata at the marsh! Credit goes to Meg Sked for this beautiful photo, and to my son CJ for capturing it!
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Elegant Spreadwing
The Elegant Spreadwing (Lestes inaequalis), true to its name, is a beautiful damselfly seen occasionally at Spring Lake and in areas along the back Island of Roebling Memorial Park. Species in the Spreadwing family (Lestidae) earned their name because of how their wings are spread while perching. Elegant Spreadwings are larger than many damselflies but (in my experience) may not be as conspicuous because may be rather shy, and often prefer slightly shadier areas. Other species of Spreadwing are more common in New Jersey, so having the Elegant Spreadwing as a denizen of the marsh is a nice treat for Odonata enthusiasts.
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Mocha Emerald
The Mocha Emerald (Somatochlora linearis) is a relentless flier and was difficult to capture. The adults of this species, as well as many species in the Emerald family (Corduliidae) have beautiful, emerald-green eyes contrasting against a dark body. This species was seen briefly in June at two Abbott Marsh locations in Burlington County, and the specimen in this picture was captured at Bordentown Bluffs. Like other fliers, they hunt on the wing, and like other dragonflies, one of their favorite meals is a mosquito (which is one more reason to love dragonflies). If you visit the Abbott Marsh in the summer and see a long, thin, dark dragonfly circling overhead, never seeming to land, it may be a Mocha Emerald!
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