Damselflies belong to the suborder Zygoptera. They are slender-bodied insects with eyes set far apart, giving them a “hammer-headed” appearance. Most have a coloured eyespot on the back of each eye. The easiest way to tell a damselfly from a dragonfly is the way they hold their wings when perched: all four wings are usually held together alongside or parallel to the abdomen, while dragonflies hold their wings out at right angles like an airplane. The exception to this is the group known as spreadwings, which are slightly larger damselflies which hold their wings out at 45° degree angles when perching.
Damselflies are weak fliers, and are thus not usually found too far from water. Damselflies eat mostly flying insects such as mosquitoes, flies, moths and beetles. They typically hunt by perching on a leaf or twig and then ambushing prey that fly into view. They can also catch prey while on the wing; their legs, which are covered in bristles, are tilted forward, so that the bristles interlock and form a net that can be used to catch insects in flight. The front pair of legs are short, allowing damselflies to raise the captured prey to their mouths while flying.
Our most common and widespread species of damselfly is the Eastern Forktail. Not only is it the earliest damselfly on the wing each spring, it has a long flight period and can often be found well into the fall. They inhabit virtually any freshwater pond, lake or slow stream where they can be seen low among vegetation near or at the shore. Eastern Forktails can be found in three colour forms.
Males, such as the one shown above, and some immature females have a black and green thorax and a black abdomen ending with two blue segments on segments 8 and 9. The shoulder stripes and eyespots are green.
Most immature females, however, are orange and black. The thorax and first three segments are mostly orange, while the remaining abdominal segments are all black above. Immature females have black shoulder stripes and orange eyespots.
Older females develop a grayish-violet pruinosity on their bodies and bright green eyes. They are our only damselfly with this gorgeous colouration.
The other forktail species you are likely to encounter in the Ottawa area is the Fragile Forktail, a small black and green damselfly that looks like a male Eastern Forktail without the blue-tipped abdomen. The green (or blue, in females) exclamation point (!) pattern on the thorax is a key field mark in identifying this species. Though not as common or widespread, I tend to find them wherever I go – except when Bob and Chris ask me to find one for them! The Fragile Forktail was the first damselfly I’d seen in my yard, which is a good couple of kilometres from the nearest water, a couple of storm water management ponds just outside of our subdivision. This individual was found in the vegetation by those storm water ponds on July 1st.
The Powdered Dancer is a large damselfly found near rocky streams and rivers. As its name suggests, this damselfly develops extensive pruinosity on its head, thorax, and both ends of its abdomen. They are called Dancers because of their distinctive bouncing (“dancing”) flight. Young males are pale brown with a mostly black abdomen and become black and white over time.
Females come in two colour forms, one brown and one blue. In some parts of the east dancers may be confused with other damselflies, such as bluets; however, they can always be distinguished from other pond damsels by the long bristles (called setae) on the front of their tibiae (the middle segment of their legs), which are twice as long as the intervening spaces. In all other damselflies, the setae are only about as long as the spaces between each bristle. The long setae are visible in the photo below.
The bluets are a challenging group of pond damsels that are difficult to identify. Most of them are blue and black, and a general rule of thumb is that the more black they have in the abdomen, the easier they are to identify them in the field (note – this only works for males). Otherwise, they will need to be examined in the hand with a good magnifying lens in order to view structural features.
One of the most common species we have along the Ottawa and Rideau Rivers is the Stream Bluet. The male’s abdomen is mostly black, with thin blue rings on segments 3 through 7, and an entirely blue segment 9. Segment 8 is blue with a narrow black triangle on the dorsal side pointing toward the tip. Stream Bluets have thick black shoulder stripes that are wider than the blue stripes and small blue eyespots joined together by a thin occipital bar.
The Rainbow Bluet is another easily identifiable bluet with a mostly black abdomen, except this species features almost all the colours of the rainbow! Males have an orange face, orange eyes, and small blue eyespots joined together by a thin occipital bar. The underside of the thorax is green, while the top is black with narrow yellow shoulder stripes. The legs are yellow, the tip of the abdomen is blue, and the wings are clear with orange stigmas.
Females are similar in appearance but more greenish, and the colours are more subdued; they aren’t as bright and boldly coloured as the males. They also have a different pattern on segments 8 through 10, the most obvious of which is the narrow blue line on segment 9 pointing toward the tip.
These striking damselflies prefer rivers with a slow current, muddy bottom, and emergent vegetation. There is a good-sized colony at Hurdman Park, and in mid-June I found several males in the vegetation right next to the river. I also found a few in the vegetation along the storm water management ponds near my house on Canada Day.
The spreadwings are one of my favourite groups of damselflies. They are larger than the pond damselflies, and perch with their wings partially open. Some of them are a brilliant metallic green colour, while others are black and bronze or powder blue. They prefer small, still-water environments such as beaver ponds, quiet bays along lakes and rivers, and roadside ditches. Look for them perching on vertical stalks of vegetation with their bodies pointing down at an angle.
Male spreadwings can be identified by the shape of the claspers, which are often visible in the field upon close inspection. The upper claspers of all our local spreadwing species come together to form a semi-circle; it is the shape and size of the lower claspers that differentiates them (see the arrow below). The lower claspers of this fellow are shorter than the upper claspers also form a semi-circle, although he was opening and closing them while I was photographing him. This points to Emerald Spreadwing rather than Elegant or Swamp Spreadwing, which are also metallic green in colour but are found in more restricted habitats.
The Emerald Spreadwing is considered uncommon, though I’ve found them along the trails of Stony Swamp and in other places on several occasions. This fellow was photographed at Jack Pine Trail on Canada Day. Emerald Spreadwings are small and stocky in size compared to the other metallic green spreadwings. The underside of the thorax in younger Emerald Spreadwings is pale yellow, though males develop a grayish-blue pruinosity as they age. The tip of the abdomen also turns grayish-blue.
Although small, damselflies are definitely worth paying attention to. Look for them lurking in the vegetation near water, perching on lilypads and floating vegetation, or resting on the ground. They are easier to approach than dragonflies, particularly if they are busy eating, and if startled they usually don’t fly too far (although the speed with which they fly off can be startling)! They are beautiful and fascinating creatures, well worth getting to know.