“…and today we’re asking hoo is this bug? But more on that later.”
In nature, mimicry allows some creatures to ride the coat tails of others. You get the aura–the vibe of a dangerous, poisonous, or disgusting critter without having to put in the hard work of developing those traits. But the Giant Owl Butterfly takes it to another level–in some cases looking like a photorealistic copy of a frightening predator. But imitation is the sincerest form of flattery in Life, Death, and Taxonomy.
Description of the Giant Owl Butterfly
- Picture a flying throw rug in earthy browns and beiges, camouflaged like it just rolled out of a compost pile
- Wings broad and floppy, etched with wavy tan bands and subtle veins that look like sand washed by the waves on the beach
- Body squat and scaly-fuzzy, like a velvet baby carrot with spindly legs
- Antennae hooked like little shepherd’s staves
- Females bulk up bigger than the males
Measure Up
Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com.
A Bug’s Life – “I’m a beautiful butterfly” – Heimlich (HD)
Wingspan of the Owl Butterfly
The Owl Butterfly (Caligo eurilochus or similar large species) has a wingspan of 6.3 inches (16 cm). How many objects fit into the butterfly’s wingspan (if the object is shorter) or how many butterflies fit into the object’s length/diameter (if the object is longer)?
a) The length of a Costa Rican cacao pod
A mature cacao pod from Costa Rica (where owl butterflies are common) measures about 20 cm (7.9 inches) long.
b) The diameter of a traditional Amazonian blowgun dart
A Curare-tipped dart used by indigenous hunters in the Amazon measures about 25 cm (9.8 inches) long including fletching.
c) The length of a blue morpho forewing
A single forewing of the famous blue morpho (Morpho peleides), often seen flying alongside owl butterflies, measures about 7.5 cm (3 inches).
Question: How many fit into each wingspan comparison?
A) 2.3 Owl Butterflies go into the length of a Costa Rican cacao pod
B) 3.6 Owl Butterflies go into the length of an Amazonian blowgun dart
C) 2.1 blue morpho forewings go into the wingspan of an Owl Butterfly
Body Length of the Owl Butterfly
The Owl Butterfly has a body length of 2.2 inches (5.6 cm). How many objects fit into the butterfly’s body length (if the object is shorter) or how many butterflies fit into the object’s length (if the object is longer)?
a) The length of a harpy eagle talon
A rear talon (hallux) of a harpy eagle (Harpia harpyja), the top predator in the same neotropical canopy, measures about 10 cm (3.9 inches).
b) The diameter of a passion flower (Passiflora)
A typical passion flower (a host plant for many Caligo caterpillars) measures about 10–12 cm across; we’ll use 11 cm (4.3 inches).
c) The length of a single bromeliad leaf
A narrow leaf from a tank bromeliad in the Costa Rican rainforest (where owl butterflies roost) measures about 4 cm (1.6 inches).
Question: How many fit into each body length comparison?
A) 1.8 Owl Butterflies go into the length of a harpy eagle talon
B) 3.0 Owl Butterflies go into the diameter of a passion flower
C) 2.4 bromeliad leaves go into the body length of an Owl Butterfly
Fast Facts about the Giant Owl Butterfly
- Range: Steamy tropics from Mexico’s edges through Central America to the Amazon sprawl in South America, basically anywhere with enough humidity to steam your glasses
- Habitat: Lurks in the dim underbellies of rainforests and scrubby second-growth woods, where the shade’s thick and the banana buffet’s ripe.
- Diet: Adults slurp fermented fruit mush—bananas are the house special—while fat green caterpillars chew banana leaves, occasionally crashing the local farm party as pests
- Mating behavior: Males puff out pheromone clouds like cheap cologne and flutter in to court the females
- Lifespan: The full egg-to-dust cycle drags on 4-5 months, but adults cash out in 1-2 weeks, proving even fakers gotta fade fast
- Social behavior: Mostly lone wolves, though they might cluster during feeding
- Predators: Birds, lizards, chameleons, frogs, and toads that aren’t buying the tough-guy act and lunge anyway, turning showtime into chow time
- Fun fact: They only hop a few meters at a pop, like they’re too lazy to commit to escape.
Major Fact: Owl See My Way Out
The owl mimicry in Caligo telamonius (and other Caligo species) is one of the most dramatic and effective examples of defensive mimicry in butterflies. It is aimed almost entirely at deterring vertebrate predators—especially insect-eating birds and small mammals—in the dim understory of tropical rainforests.
The owl butterfly’s underwings are great at blending in (cryptic camouflage), but those big “owl eye” spots on the top side have puzzled scientists for ages.
The spots look a lot like big predator eyes (light ring around a dark center). Many small animals get nervous and stay away from anything that looks like that.
One long-standing idea is that the whole pattern makes the butterfly look like the head of something bigger and scarier—like a lizard, owl, or frog—especially when it’s sitting still, eating, mating, or just out of its cocoon.
In some butterflies, similar spots act as decoys: if a bird attacks, it goes for the fake eye on the wing instead of the butterfly’s body.
In a 2008 study, Scientists tried to determine if the big “owl-eye” spots on butterflies (and other animals) scare off birds because they look like real eyes, or do they work just because they’re big, bright, and stand out?
They tested this in the wild using fake “prey” (little pastry-like baits on leaves) marked with different patterns and left them for birds to attack.
What they found:
- The patterns that survived best had lots of spots and big spots.
- Circles (which look like eyes) were no better than bars, squares, or other bold shapes.
- Making the spots look more like real eyes (perfect circles with rings, placed like a face) didn’t help at all.
They concluded, birds aren’t scared because the spots look like eyes. They’re put off simply because the markings are large, numerous, and highly conspicuous. So the classic “eye-mimicry” idea doesn’t hold up in this test — it’s the “whoa, that’s bright and weird” effect that protects the butterfly.
But why does it look so much like an owl?!
Ending
So hang out on your own, enjoy some ripe ripe fruit, and imitate the wisdom of the owl like the giant owl butterfly here in LDT.