For those of you who avoided our recent dragonfly quiz, and for those who played the game but felt uneasy, here is an observation primer. As with all new subjects, it takes time to get one’s bearings, but there are some easily observable aspects of appearance and behavior that can point you in the right direction.
The title of my July 29 post “Dragonflies and Damselflies” grouped these two sets of animals together because they both belong to the insect order Odonata. Odonates (“Odes”) are predatory insects whose larvae develop underwater. They possess large compound eyes, biting mouthparts (for their prey), membranous wings, and slender abdomens. Because of their shared lineage, life cycle, habitats, and behaviors, the two suborders are often seen and studied together. The first step in identification is learning to distinguish between the two groups.
Compare these two images.
|Blue Dasher, Easton, July 25, 2022||Bluet sp., Plymouth, August 1, 2020|
The insect on the left holds its wings straight out to the sides; the damselfly’s wings are held over its back. Notice that this dragonfly’s eyes are so close together that they meet at a seam. In contrast, the damselfly’s eyes are widely spaced and almost look “stalked.” The damselfly’s abdomen is more slender, giving it a delicate appearance. Dragonflies are stronger flyers and spend more time in the open.
I would advise newcomers to begin with dragonflies, particularly species in the skimmer family which are common, colorful, and more easily observed. The differences between these species can be seen with one’s eyes, a pair of binoculars, or from photos taken in the field. My examples will be mostly from this group.
When trying to identify the insect that just flew by, one is likely to recall its color. This can be very striking as in the image below where the eastern amberwing fairly glows in the sunlight. On the other hand, many species share the same color range, and light levels can affect our perception of color. While members of the skimmer family tend to be showy, noticing just their primary color will be insufficient to reach an ID.
Eastern Amberwing, Pembroke, August 6, 2022
This is a characteristic that can be discerned even when light levels are not optimal. With practice, it will be easy enough to sort your sightings into small, medium, or large. Measured from the front of the head to the tip of the abdomen, the eastern amberwing is less than 1 inch. It is quite small. In the next photo, the individual is perched on pineweed, a diminutive plant that is about 4-5 inches tall.
|Small: Eastern Amberwing, Hanson, August 22, 2021|
The slaty skimmer measures 2 inches. My insect is perched on a mullein seed head that is about 1 inch in diameter. Many other skimmers have lengths between 1.25 and 1.75 inches. I would deem this size “medium.”
|Medium: Slaty Skimmer, North Easton, August 17, 2021|
Some Massachusetts dragonflies are noticeably large: 2.5 to 3 inches . . . or more! The common green darner is a familiar example of one of these king-sized species. The specimen in this image is perching on a sturdy branch rather than a frail wildflower.
Large: Female Common Green Darner
Eugene Zelenko, CC BY-SA 4.0
Before you stress about the fine details, pay some attention to the obvious. Where did you observe the dragonfly? A pond? Was it large or small, deep or shallow, sandy- or muddy-bottomed? Or, did you see the insect at a woodland stream or in an open meadow? Perhaps even a salt marsh? While some species utilize a variety of wetlands, others have a clear preference. Habitat will be noted in a good field guide. Here are a few examples.
The ebony jewelwing (a damselfly) will be found near shallow forested streams. The insect in this photo, along with many other jewelwings, fluttered around vegetation along the fast-moving Machias River.
Stream: Upper Machias River, Maine, July 11, 2021
In contrast, the blue dasher prefers the quiet water of well-vegetated ponds. What’s more, the naiads “are very tolerant of water that is polluted or has low levels of dissolved oxygen” according to The BugLady of the University of Wisconsin. I bet the naiads in Queset Garden’s tiny, stagnant pool were blue dashers. This species is the most commonly reported dragonfly on iNaturalist for Bristol County.
|Weedy Pond: Blue Dasher, North Easton, August 15, 2022|
Some dragonflies and damselflies prefer, if not require, the special coastal plain ponds of Southeastern Massachusetts. Unlike many local ponds, the depth of these water bodies depends on fluctuating groundwater levels. No streams replenish them. These ponds have low nutrient levels, high oxygen, acidic pH, and often sandy bottoms. They support a host of rare plants that can adapt to these specific conditions, and they are especially rich in Odonates. Myles Standish State Forest is ground zero for coastal plain ponds . . . and a spectacular place to observe damselflies and dragonflies.
|Coastal Plain Pond, Myles Standish State Forest, August 1, 2020|
All dragonfly larvae require water, but the adults of some species forage for food over dry land. One such group are the meadowhawks, late-season, mostly red dragonflies that often visit fields.
Judy Gallagher, CC BY 2.0
Simply noting the season can be helpful in narrowing your identification options. While dragonflies may be observed from spring through fall, each species has its own flight period. A few, like the common green darner, may be seen throughout the mild months. Other species may be active for only a month or two. A good field guide such as The Stokes Beginner's Guide to Dragonflies and Damselflies, will include each species’ flight period.
Knowing which dragonflies could be actively flying will help you eliminate some species as you work towards an identification. If you keep a nature notebook or take photographs, be sure to label your observations with date, time, and location . . . before you forget!
Here are a few examples. The chalk-fronted corporal peaks in Massachusetts during June/early July. Its range doesn’t include Southeastern Massachusetts, but its cousin, the white corporal, does live here.
|Chalk-fronted Corporal, Machias, Maine, July 11, 2021|
July/early August is the time to see the golden-winged skimmer, a dweller of coastal plain ponds.
|Golden-winged Skimmer, Plymouth, August 1, 2020|
For late season viewing, stay alert for the yellow-legged meadowhawk, also known as the autumn meadowhawk. This species doesn’t begin adulthood until late July. It is the last adult dragonfly of the season.
Judy Gallagher, CC BY 2.0
Compared to other dragonfly families, skimmer species spend more time perching. Noticing how and where they perch provides clues to their identification.
If your specimen is perched horizontally on the ground, a log, or a rock, it might be one of these species.
|Eastern Pondhawk Pembroke, July 31, 2022 Common Whitetail|
On the other hand, some dragonflies hang vertically from vegetation. See the green darner above.
Others, like the slaty skimmer, tee up or hang obliquely on vegetation.
|Slaty Skimmer, Easton, August 17, 2021|
Slaty Skimmer, Easton, July 2, 2022
Notice, also, how the insect holds its wings when perched. The blue dasher’s wings often droop downward.
|Blue Dasher, Easton, July 23, 2022|
Equally helpful is the dragonfly’s manner of flying. Does it flutter or dart? Does it fly near the surface or high in the air? How often does it perch and for how long? Does its flight remind you of another animal’s? Perhaps it moves like a wasp, a butterfly, or a hawk.
Now for some of the nitty gritty. Many of the fine points of identification are based on color patterns. Let’s start with wings.
The eastern pondhawk has very little color on its wings.
|Wings: Little to No Color|
Eastern Pondhawk, Pembroke, July 31, 2022
In contrast, the wings of some species, like the amberwing, are one solid color.
|Wings: Solid Color|
Eastern Amberwing, Easton, July 27, 2022
Many species have patches, bands, or dots. Paying attention to the number, shape, and color of these patches will point you towards the correct insect. The male blue dasher has pale tan patches towards the wing tips and near the body. Whereas the male common whitetail has prominent dark bands towards the tips and small dark patches near the body. Both insects have powdery-blue abdomens, but their wings are strikingly different.
|Wings: Pale Patches||Wings: Dark Bands|
|Blue Dasher||Common Whitetail|
Speaking of the whitetail . . . the male’s solid-color abdomen is also conspicuous, even from a distance and without binoculars. Compare this to the black and green pattern of the female pondhawk’s abdomen.
|Abdomen: Solid||Abdomen: Pattern|
|Common Whitetail||Eastern Pondhawk|
If you have binoculars, or are fortunate enough to get a close look, you will also begin to notice patterns on a dragonfly’s thorax, that is, the middle part of body where the legs and wings connect. This thorax of this blue dasher has stripes on both the top and the sides.
Blue Dasher, Easton, August 15, 2022
Before we leave the subject of patterns, let’s consider one more feature that contributes to a dragonfly’s overall appearance: stigmas. You have probably noticed this anatomical feature, even if you didn’t know its name. Stigmas are those colored cells near the tips of each wing. I have read that their weight gives stability to the dragonfly’s flight, thereby enabling faster speeds. The stigmas on this male blue dasher make its wings stand out.
|Blue Dasher, Easton, August 15, 2022|
These tiny rectangular spots come in different colors including black, white, red, brown, and yellow.
Needham’s Skimmer?, Pembroke, June 20, 2022
|Eastern Amberwing, Easton, July 27, 2022|
As you’ve been reading this post, you might have wondered why dramatically different insects were given the same name. Did she make a mistake? Perhaps. I am certainly not accomplished in this field. Part of the confusion, though, was intentional. I have some discouraging news for the beginner dragonfly observer: often you’ll need to learn two sets of field marks for every species. Adult males don’t look like females or immature males. Sorry. On the bright side, this adds a lot of beauty to our world and some interesting challenges.
Here are two species that demonstrate sexual dimorphism.
|Green Females; Blue Males|
|Eastern Pondhawks, Pembroke, July 31, 2022|
|F: Dark Abdomen with Green Stripes||M: Blue Abdomen with Black Tip|
A FINAL NOTE
As you can see, the process of identification depends as much on the observer’s behavior as it does on the animal’s! What you notice, which questions you ask yourself, and how you assemble the available information make a huge difference. Think of it as a puzzle: with enough of the pieces, the image becomes clear.
Now you’re ready to give that Dragonflies and Damselflies game a try . . . and to do some dragonfly spotting of your own.
Recommended Field Guides:
The Stokes Beginner’s Guide to Dragonflies and Damselflies (Commonwealth Catalog)