Published in Malaysian Naturalist 77 4 (June 2024)
Why are there many more moth species than butterfly species?
Rosli Omar
rosliomar@fastmail.fm
19 July 2024
Ever since I dove into the animal order of Lepidoptera, the world of moths and butterflies, I’ve been intrigued by the vast disparity between the number of moth species and those of butterflies. Globally, there are some 160,000 species of moths and 19,000 species of butterflies. That is, nearly 10 times more moth species than butterflies. For Peninsular Malaysia, there are 1048 butterfly species (see Corbet and Pendlebury, 5th edition (2020) or C&P5. They actually list 1051 species but three are exclusive to Singapore. Another one listed as also exclusive to Singapore has since been discovered in Johor according to the ButterflyCircle blog). The corresponding number of moth species for Peninsular Malaysia is around 10,000. Again, about 10 times more moth to butterfly species.
Antheraea larissa moth.
Callidula sakuni, a day-flying or diurnal moth.
Tropical Swallowtail Moth. Lyssa zampa. A big moth, it is easily spooked to fly off on approach.
Colonel butterfly. Athyma sinope sinope. Sarjan Kuning.
White Dragontail butterfly. Lamproptera curius curius. Membara Naga-Putih.
Yellow Banded Awl, a skipper butterfly. Hasora schoenherr chuza. Penusuk Jalur Kuning
The natural question that follows is, why are there more moth species than butterfly species?
My internet search using DuckDuckGo.com, Microsoft Bing.com and Google.com, as well as consulting entomologists, have not provided a satisfactory answer. The much-vaunted artificial intelligence-based Copilot of Microsoft came up with an answer that looked impressive on the surface, but in the end, turned out to be a non-answer. I quote it here in full:
Why are there more moth species than butterfly species?
Sent by Copilot:
Ah, the enchanting world of Lepidoptera—the order that houses both butterflies and moths! Let’s unravel the delicate mystery of why moths outnumber butterflies like a star-studded night sky. 🦋🌙
- The Grand Census:
- Imagine a global insect census. Clipboard in hand, we count:
- Butterflies: A mere 14,000 species [Encyclopaedia Britannica] flutter their way through sun-kissed meadows, their wings adorned with vibrant hues. They’re like the elegant guests at a garden party—dainty, colorful, and always camera-ready.
- Moths: Hold your breath—there’s a whopping 160,000 species of moths! These nocturnal wanderers span various families and habitats. Some are like cryptic messages etched on tree bark; others flaunt their fuzzy elegance. They’re the night owls of the Lepidoptera family, circling porch lights and weaving secrets in moonlit forests.
- Imagine a global insect census. Clipboard in hand, we count:
- The Butterfly Ballroom vs. Moth Masquerade:
- Butterflies: Picture a ballroom. Butterflies waltz in, wearing their finest—dazzling wing patterns, slim bodies, and simple club-tipped antennae. They’re the prima donnas of the insect world, flitting from flower to flower, sipping nectar, and gracing us with their presence.
- Moths: Now, imagine a masquerade. Moths arrive—some in drab attire, others in striking costumes. Their bodies are stout, often fuzzy, and their antennae? Oh, they’re the real showstoppers! Feathery, thick, and intricately designed. These antennae are like cosmic radio receivers, tuning in to moonlight symphonies and hidden scents.
- The Night Shift:
- Moths: They’re the night shift workers—the ones pollinating night-blooming flowers, like secret agents exchanging nectar codes. Their muted colors blend seamlessly with moonbeams, and their fuzzy wings carry ancient tales.
- Butterflies: Daytime divas, they flaunt their colors under the sun. But when twilight descends, they retreat, leaving the stage to their moth cousins.
- The Caterpillar Connection:
- Both butterflies and moths start as caterpillars—those quirky, munching larvae. They nibble on leaves, grow plump, and eventually transform. Caterpillars are like the backstage crew—they build the sets (cocoons or chrysalides) for the grand transformation.
- The Evolutionary Tango:
- Moths have been around since the dinosaurs were practicing their moonwalk. They’ve adapted to diverse ecosystems, from rainforests to deserts. Their survival strategy? Camouflage, mimicry, and a dash of lunar mystique.
- Butterflies, though newer on the scene, have mastered the art of daytime elegance. Their courtship dances involve flower petals, sunbeams, and a touch of pollen romance.
So, my curious friend, moths outnumber butterflies because they’ve mastered the night shift, whispered secrets in ancient forests, and danced through eons. Next time you see a moth fluttering by, give it a nod—it might be carrying a message from the moon. 🌟🦋🌌”
The conclusion, as I italicised above, is poor reasoning from a long, fancy, premise, i.e. all the stuff before the actual conclusion. There are glimpses in there into a more plausible answer, which I will now attempt to flesh out.
The first reason for moth species outnumbering butterflies is that they emerged first in the world, millions of years earlier, as Copilot tries to say. According to Mark Stevens of the University of Adelaide, Australia, moths are twice as old as butterflies. Butterflies appeared about 100 million years ago, evolving from moths. This allowed moths a head start in evolving a greater number of species.
Another reason, as Copilot tries to say too, is that moths are creatures of the night (although some are day-flying) whereas butterflies are largely diurnal. Only some butterflies, usually the skippers, are active during dawn and dusk, the crepuscular behaviour. Given that they are insects, which are more active in the presence of sunlight, the nocturnal moths are less active compared to butterflies. Thus, their territorial ranges are smaller – they can’t fly as far. Hence, for any given area, there are more micro-niches or micro-habitats for moths than butterflies. More micro-habitats mean more species are possible.
Thirdly, there is the existence of ‘micro’ moths, the very small moths or microlepidoptera. Given their small sizes, their territorial ranges are smaller than those of the bigger butterflies, again giving rise to more micro-habitats and thus a greater number of species. In the Peninsula, half of moths are micro moths.
So, these three reasons ̶— an evolutionary head-start; being insect creatures of the night ̶leading to more micro-habitats; and the existence of micro moths also leading to more micro-habitats — explain why there are more moth species than butterflies. Whether this is enough to explain all needs further discussion.
Acknowledgements
Thank you to Tan beng hui and Mike HN Chong for reading through the article and providing valuable comments. Any shortcomings are my own.
Further Readings
1. Globally, there are some 160,000 species of moths. https://www.si.edu/spotlight/buginfo/moths
2. 19,000 species of butterflies in the world. https://theconversation.com/how-butterflies-conquered-the-world-a-new-family-tree-traces-their-100-million-year-journey-across-the-globe-205487
3. For Peninsular Malaysia, there are 1048 butterfly species. See, Corbet, S.A. and Pendlebury, H.M. (2020), The Butterflies of the Malay Peninsula. 5th edition, edited by GM & NE van der Poorten. Malayan Nature Society: Kuala Lumpur (C&P5).
4. A species listed as exclusive to Singapore by C&P5 has been discovered in Johor. https://www.butterflycircle.com/checklist/showbutterfly/35
5. The number of moth species for Peninsular Malaysia is about 10,000, with half being micro moths. https://www.researchgate.net/publication/370006410_Lepidoptera_Collecting_in_Malaysia_The_Genting_Tea_Estate_Experience
6. Moths are twice as old as butterflies. https://theconversation.com/unveiling-the-enigmatic-world-of-moths-from-ancient-pollinators-to-whistling-wonders-209590
7. Butterflies appeared about 100 million years ago, evolving from moths https://www.si.edu/spotlight/buginfo/moths
8. The very small moths or microlepidoptera. https://theconversation.com/unveiling-the-enigmatic-world-of-moths-from-ancient-pollinators-to-whistling-wonders-209590
9. Malay names to the butterflies can be obtained from my butterfly checklist for Peninsular Malaysia: https://rosliomarphotography.com/butterfly-checklist-of-peninsular-malaysia/
Rosli Omar is author of Birds of the Forest of Peninsular Malaysia: a photographic guide (SIRD, 2018), and co-author of Butterflies of Peninsular Malaysia: with a checklist of scientific, English and Malay names (Ministry of Natural Resources, Environment, and Climate Change, 2023). Although educated in electrical engineering and artificial intelligence, his passion is for nature and its conservation. He was previously a lecturer at Universiti Malaya before taking early retirement to focus on wildlife photography.