Identifying Larvae to Family
This page should be primarily used as a general guide, not a key
in trying to identify to family. As a beginner, using entomology textbooks
can be difficult due to the use of unfamiliar terminology; however I strongly advise
you to develop those skills necessary to accurately identify your odonate.
Trying to identify larvae can be especially difficult if you are unfamiliar with
scientific terms. We have included labeled drawings of typical larvae in our
larval anatomy and physiology section to help you learn these parts.
In most cases, photos of exuviae have been used since they may be found without
damaging the habitat. Additionally, they sit still, larvae don't!
DRAGONFLY LARVAE
Petaltails (Petaluridae)
Petaltail larvae are generally short with thick hairy 7-segmented antennae that
are shorter than the head. The labium is flat; the palps are broadened partially
covering the face. The palpal lobes have a large spur at the base of the moveable
hook; their legs appear twisted. These larvae are semi-aquatic, sedentary and mostly
nocturnal. They wait in the muck in seepage waters for prey to come their
way.
Darners (Aeshna)
These larvae are generally smooth, slender and very long. The head appears
flattened with 5-7 slender bristle-like antennae which are similar and size and
shape. These particular larvae have well developed eyes that are positioned
laterally on the head. The labium is very long and flat when viewed laterally
and is held under the head not in front of the face like in our larvae. The
prementum and palpal lobes are flattened. The thorax is slightly depressed
while the abdomen is slightly widened from the base to beyond the middle, than narrowed
at the end. Some species may even present with sharp lateral spines on segments
5-9. Legs are long and thin. These larvae are mostly brown in coloration
but may be mottled, speckled, banded or spotted in darker shades. They are
found in slow moving streams, rivers, ponds and marshes. They are predators
that climb through vegetation and stalk their prey. They are probably the
most voracious of all dragonfly larvae.
Clubtails (Gomphidae)
Clubtail larvae are robust, and have wedge shaped heads and thick 4-segmented
antennae with the 3-segment extended and generally flattened, thick and club-like,
while the 4-segment reduced. The antennae never develop more than (4) segments.
The labial mask is not spoon-like, like other larvae but flat when view laterally.
They have strong modified legs that are extended slightly to the side enabling them
to borrow. The fore tarsi are 2-segmented, unlike other odonates which have (3).
Their coloration is generally that of a brown to dull green. Clubtail larvae
are both sprawlers and burrowers concealing themselves in the sand, mud and gravel
of fast moving streams and rivers. Emergence generally takes place in a number
of areas close to the water and exuviae can often be found on such structures as
bridges, tree trunks and rocks.
Spiketails (Cordulegastridae)
These larvae are cylindrical and flattened in shape and short in length.
The head is broad and flat on the upper-side with a rounded shelf-like prominence
between the bases of the short antennae. The labium is mask-like. The
eyes are set forward on the head. The abdomen has no mid-dorsal keel, but
has a well developed lateral keel. The legs are hairy, but become bare and
heavily spinned near the end of the tibia and at the end of the basal segment of
the tarsi. These larvae are generally brown in coloration. They are
wait for prey predators and can usually be found submerged up to their eyes in sand,
soft muck and silt bottom seeps or woodland streams usually where is only a slight
flow of water. They are long livers and require at least 3-4 years in which
to develop into adults.
Cruisers (Macromidae)
These larvae have a spider or crab-like shape. They are unique in that
they have a protruding triangular horn on there forehead in between their eyes,
and a short spoon shaped labium that partially covers the face. The entire
body appears very flat and broad with a median row of high, laterally flattened
dorsal hooks down the back, with short and stout caudal appendages. They have
very long slender legs with their tarsi bearing very long slender and simple claws.
Cruiser larvae are well concealed by colorations of mottled grays and browns. These
larvae are sprawlers, and inhabit bottom sand and silt in the shallows of lakes,
streams and rivers. They sprawl in the bottom debris and wait for prey to
come their way. These larvae emerge at night crawling onto vegetation or structures
such as bridges, docks and buildings and emerge while vertical.
Emeralds (Corduliidae)
Emerald larvae are generally short and robust, with wedge shaped heads and a
spoon-like labium with a labrial mask that covers the face almost to the eyes.
They have long sharp spines running down the back and top to the terminal end of
their abdomen, with long protruding legs. The labial palps are toothed or notched
distally. Those of Libellulidae remain distally smooth throughout development.
This characteristic can be an aid in differentiating the two. Some larvae species
to this family are sprawlers, where they lie on the sand or soft muck in woodland
stream bottoms waiting to ambush unsuspecting prey, while others are climbers making
there way among vegetation looking for prey. The sprawling species are generally
of dark coloration, while the climbers appear smooth and patterned with browns and
greens. Generally larvae inhabit bogs, fens, ponds and small lakes.
Emerald larvae can very easily be confused with skimmer larvae due to their shape
and coloration and can only be accurately identified by using a good text with a
larvae key.
Skimmers (Libellulidae)
These larvae are generally stocky, wide and short. They appear to have
a wide head with a spoon-shaped labium that covers the lower half of the face.
The abdomen is adorned with a coating of fine hair. They are generally camouflaged
in colors of green, olive and shades of brown. The majority of skimmers are
sprawlers with only a few species that prefer to burrow in mud. They inhabit
ponds, lakes, ditches and almost any body of water.
DAMSELFLY LARVAE
Broad-winged Damselflies (Calopterygidae)
Larvae of broad-winged damselflies are relatively long, thin and large.
They are easily identifiable by their long antenna. The first segment of the
antenna is longer than the combined length of remaining antenna. The prementum
is with a diamond shaped medial cleft. The terminal end of the abdomen has
three long leaf-like gills (caudal gills). The lateral lamellae are longer
than the middle lamellae. These larvae are dark in coloration and inhabit
edges of slow streams and rivers. They can often be seen climbing through
vegetation.
Spreadwings (Lestes)
Spreadwing larvae are very long and thin. All segments of their
antenna are approximately the same in length. They have a prementum with small
triangular notch. The prementum is stalked and spoon shaped. The terminal
end of the abdomen presents with three leaf-like gills (caudal gills) that are similar
in length. Veins in the gills are visible and perpendicular to
medial line. These larvae are most common in small ponds, bogs, wetlands,
and sometimes in slow weedy streams.
Pond Damsels (Coenagrionidae)
The smallest of all damselfly larvae, with large prominent eyes and a short
antenna. All the antenna segments of the narrow-winged damselflies are approximately
the same length. The prementum is trianglular and stout without medial notch. The
labium is almost triangular in shape. Palpal lobes terminate in 1-2 hooks.
The terminal end of the abdomen presents with three leaf-like gills (caudal lamellae)
all in similar length with veins that radiate diagonally from medial line.
These larvae are found in rivers, lakes, streams as well as marshes and ponds.
They are predators that climb through vegetation looking for prey that consists
of various small animals.
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