Dragonflies vs. Butterflies Part 1: First Comes Form

Both dragonflies and butterflies are large, colorful creatures that naturally capture people’s attention as they fly around living their lives. Both are insects, which mean they share many characteristics in common, such as having six legs, but if you look closely, they look different from each other.

Dragonflies and butterflies differ in nearly every way. Although both are large, flying insects, they have different wings, legs, senses, life cycles, and lifestyles. For these reasons, dragonflies are classified in order Odonata and butterflies in order Lepidoptera within class Insecta.

This post is the first in a two part Now I Wonder series and focuses on the physical, visible differences between these two orders of insects.

For more information about how their physical differences dictate how dragonflies and butterflies live their lives, check out the second post in this Now I Wonder series, Dragonflies vs. Butterflies Part 2: Second Comes Function.

A blue dasher dragonfly (Pachydiplax longipennis) perched on the end of a twig. This insect has bright, metallic-looking green eyes and a pale, powder-blue body. — This blue dasher dragonfly (*Pachydiplax longipennis*) shows how dragonfly legs are crowded together at the front of their thoraxes.

Dragonfly wings are narrow; butterfly wings are broad

Dragonflies and butterflies are both large insects, with two pairs of wings (fore wings and hind wings) and large wing spans, especially as compared to most other flying insects such as bees, wasps, and most beetles. Relative body size is difficult to determine because dragonflies and butterflies are shaped so differently but in general, dragonflies are bigger than butterflies when size is averaged across species.

Here is a comparison of the wingspans of a few of the most common dragonfly and butterfly species found in the southeaster United States (North Carolina, South Carolina, and Georgia).

This table shows a comparison of average wing span between two species of dragonflies and two species of butterflies common to the southeastern United States. — This table shows a comparison of average wing span between some of the largest common species of dragonflies and butterflies found in the southeastern United States.

But beyond mere size, dragonfly wings and butterfly wings are very different from each other. Dragonfly wings are long, narrow, and both pairs are about the same size and shape. Butterfly wings are broad and wide, and the hind wings tend to be more rounded compared to the fore wings. The different wing shape makes each insect instantly recognizable in silhouette.

Dragonfly wings are membranous; butterfly wings are scaled

Insect wings are made of cuticle, which is a nonliving composite of chitin and other proteins.

The cuticle of dragonfly wings is exposed; their wings are primarily transparent to translucent.

A perched dragonfly displaying the beautiful, multi-colored iridescence caused by light scattering across the wings' surfaces. — This perched dragonfly is showing off the iridescence caused by light scattering across the wings’ surfaces.

In contrast, butterfly wings are opaque because the cuticle is covered in millions of tiny, overlapping scales. These scales are unique to butterflies and moths and are the reason for the name of their scientific order: “Leptidoptera” means “scaled wings”.

A single hind wing from a swallowtail butterfly with a key for scale. The wing fragment is bright yellow, edged with a wide band of black with contains patches of iridescent blue, bright orange, and pale yellow. The wing also displays the "tail" that gives swallowtails their distinct appearance and common name. — This hind wing is from a swallowtail butterfly, who must have met an unfortunate demise. Note the rich, powdery colors formed from millions of microscopic scales which cover the entire wing surface.

Dragonfly wings are splotchy; butterfly wings are colorful

Dragonfly and butterfly wings display different colors and types of color.

Depending on the species, dragonfly wings may have markings or colored patterns but the colors rarely cover the entire wing surface and appear as patches or bands. Dragonfly wings can be iridescent if light strikes the wing surfaces at the right angle but dragonfly wings are much less colorful than those of butterflies.

Butterflies and moth wings are covered in color, thanks to their millions of wing scales. The vibrant color patterns adult butterflies display are produced by combinations of pigments, which absorb and reflect different wavelengths of light, and structural colors, which are caused by light scattering, reflecting, refracting, and diffracting at different angles.

The physical differences between dragonfly wings and butterfly wings translate into very different flight behaviors and patterns. For more information, check out my other Now I Wonder post Dragonflies vs. Butterflies Part 2: Second Comes Function.

Dragonfly legs are weapons; butterfly legs are tongues

Dragonfly legs are adapted for grasping and perching, but not for walking. Their legs are grouped far forward on their thoraxes, and bristle with spikes; they form baskets with their front legs and scoop their prey out of the air.

For more on the unique leg arrangement of Odonates, check out this other Now I Wonder post Can dragonflies walk?

In contrast, butterfly legs are adapted for walking and perching. The end segment of an insect’s leg is called the “tarsus”. Butterfly tarsi provide traction but also function as sensory organs. Butterflies taste plants through their feet to find nectar; females also scratch plant leaves with their tarsal claws then taste the damaged tissues to determine if the plants are suitable for hosting their eggs and future caterpillars (Pyle 1981).

Dragonflies bite; butterflies suck

Larval dragonflies, called “naiads” shoot parts of their mouths (called “labiums”) forward like harpoons to capture prey. Adult dragonflies lose these specialized labiums but retain sharp, chewing mandibles powered by strong bite muscles that allow them to snap and crush the hard exoskeletons of their insect prey.

In contrast, butterflies have chewing mouth parts only as caterpillars, which is the larval stage. Adult butterflies develop sucking mouth parts called “proboscises”, which are long, thin, extendable tubes through which they suck nectar from flowers. When not actively feeding, the proboscis is neatly coiled against the head and is protected by two fuzzy palpi below the eyes, which also function as sensory organs (Pyle 1981).

A sleepy orange butterfly (Eurema nicippe) feeding on a white wildfower and displaying the long, thin mouthpart called a proboscis through which butterflies and moths suck up nectar. — This sleepy orange butterfly (*Eurema nicippe*) has extended its long, thin mouthpart (called a proboscis) into the nectary of this wildflower and is sucking up nectar for food.

Dragonflies fly off, butterflies warn off

Dragonflies depend on their excellent vision and flight speed and agility to evade predators. When caught, they will try to bite with their sharp, powerful mandibles and may also attempt to stab attackers with their sharp abdominal tips. These attempts to fight back are rarely effective as most dragonfly predators are much bigger animals, such as birds and bats.

Additionally, some species can sacrifice legs if grabbed by predators; this is called “leg autotomy” (Tennessen 2009). However, despite their best efforts, countless dragonflies are caught and eaten by predators when they are not fast enough to escape through flight.

In contrast, butterflies depend on a wide variety of passive deterrents to avoid getting eaten. These include being toxic to predators, pretending to be toxic, pretending to be bigger than they actually are, startling predators into letting them go, and hiding in plain sight.

Some butterfly species incorporate noxious chemicals from their food plants into their body tissues. They then advertise their toxicity through bright color patterns that predators learn to recognize as visual warnings, which is an adaptation known as “aposematic coloration”.

One example is the black swallowtail butterfly (Papilio polyxenes), whose caterpillars absorb toxins from plants within the carrot family Apiaceae. This family includes familiar plants like Queen Anne’s lace (Daucus carota) and dill (Anethum graveolens) but also poison hemlock (Conium maculatum) and rattlesnake master (Eryngium yuccifolium)).

These caterpillars warn predators away by being bright green with black bands and yellow spots; they also have bright orange osmeteriums, forked scent glands that release foul orders when extended.

A black swallowtail caterpillar (Papilio polyxenes) advertising its toxicity to potential predators by being vivid green with black stripes and bright yellow spots. — This black swallowtail butterfly caterpillar (*Papilio polyxenes*) absorbs toxins from the food plants it eats and advertises its toxicity to potential predators through its vivid colors.

Other butterfly species are harmless to predators but deter attacks by mimicking the visual appearance of toxic species. For example, several species found in the southeastern United States look similar to the highly toxic adult form of the pipe-vine swallowtail (Battus philenor), including the black swallowtail. Pipe-vines apparently taste so bad to predators that most avoid attacking any butterfly that even looks close.

A toxic pipevine swallowtail butterfly (Battus philenor) from above showing its beautiful iridescent blue and purple coloration. — Pipevine swallowtail butterfly (*Battus philenor*). As caterpillars, this species feeds on plants such as pipevines, Dutchman’s pipe, and Virginia snakeroot and incorporates toxins produced by these plants into their own tissues. These chemicals make both the caterpillars and the adults very distasteful to many predators.

Some butterflies mimic inedible substances – especially bird droppings – to avoid notice by predators. Examples include the caterpillars of viceroys (Limenitis archippus) and red-spotted purples (Limenitis arthemis astyanax), which are splotchy white, brown, black, and green, and have horns with short, thick bristles and bumps on 4 segments (Wright 1993).

Other butterfly species use large “eye spots” to either intimidate predators or to startle them into letting go mid-attack. Examples include tiger swallowtail (Papilio glaucus) and spicebush swallowtail caterpillars (Papilio troilus), which have large, showy eyespots on the tops of their heads, and adult buckeyes (Junonia coenia), which have large, flashy eyespots on their wings.

A common buckeye butterfly (Junonia coenia) perched on white clover and displaying the large eye spots on its wings. — Some butterflies have large, dramatic spots on their wings that resemble eyes, such as this common buckeye (*Junonia coenia*). This coloration likely dissuades or startles predators these insects look bigger and more intimidating than they really are.

Conclusion

Dragonflies and butterflies are clearly different insects. They have different wings, different legs, different mouth parts, and different coloration. Each group is visually arresting in its own way; both are unique jewels that provide flashes of brilliant color to the natural world.

References

Pyle, Robert Michael. 1981. National Audubon Society Field Guide to Butterflies: North America. New York (NY): Alfred A. Knopf.

Tennessen, K. J. “Odonata.” In Encyclopedia of Insects, edited by Vincent H. Resh, and Ring T. Carde. 2nd ed. Elsevier Science & Technology, 2009.

Wright, Amy Bartlett. 1993. Peterson First Guides: Caterpillars. New York (NY). Houghton Mifflin Company.