Moths and Butterflies in 100 Seconds Transcript

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Moths and butterflies are part of the large insect order of Lepidoptera and contain around 180,000, or 10%, of all described species. Of those, moths make up the vast majority—about 160,000.

So, what's the difference between moths and butterflies anyway? Scientifically, the main distinction is that butterflies belong to the superfamily Papilionoidea—everything else in the order is classified as a moth. [56m years vs 200m years] But, the more tangible differences are that butterflies' wings tend to stay upright when resting as opposed to moths, and butterflies' antennae are long and straight compared to moths' serrated, feathery antennae. [These feathery antennae tend to serve as smell receptors.] Butterflies also tend to be diurnal and look more colorful, whereas moths tend to be nocturnal and much less conspicuous to avoid predation. Moths will often readily blend in with bark or leaves, but as usual, tropical species with predictable climates have had time to evolve into remarkable organisms.

Lepidoptera means "scale wing," which tells us something crucial about their appearance. Their wings are covered with microscopic scales so small they look like dust when touched. These scales give them color, heat retention, and help with aerodynamics. They are also responsible for some species' iridescence.

But by far the most incredible thing about moths and butterflies is their iconic life cycle. From an egg hatches a larva, which we call a caterpillar. They may spend as much as 98% of their lives as caterpillars, so the butterfly is really a lot more of a caterpillar than a butterfly. As larvae, their singular purpose is to eat and grow, typically on leaves. Because they are slow and vulnerable in this stage, many species evolved defense strategies. There's one I recorded too.

Finally, after several molts, caterpillars prepare for the most dramatic transformation of their lives. They prepare to pupate and undergo complete metamorphosis. Butterfly caterpillars typically shed their exoskeleton for the last time to reveal a hardened outer casing called chrysalis and they attach themselves to a surface from which they hang, whereas moths spin a protective silk cocoon instead.

What happens to caterpillars during metamorphosis is the most mind-blowing part of their development. The process is divided into two parts: histolysis, where the tissue breaks down, and histogenesis, where it is built from scratch. A key part of the process are imaginal discs, groups of undifferentiated cells that later become part of the adult body. During histolysis, nearly all of the caterpillar's body breaks down into a gel-like fluid—except for the imaginal discs and parts of the nervous system. The nutrients from these dead cells are then used by the cells from the imaginal discs to begin building the adult body of the insect. In other words, caterpillars' bodies quite literally dissolve and then reform from the ground up.

Once the adult Lepidopteran emerges from their chrysalis or cocoon, they have only a few weeks to live, and their focus shifts to mating. Because of how brief this stage is, some moths have no functional mouth parts at all. Most of the others act as pollinators as they sip flower nectar through their proboscis.

An exception to this pattern are migratory species like the Monarch butterfly, which survive in their adult form for 6 to 9 months as they overwinter and travel thousands of kilometers.

Fun fact: Moths get confused by artificial lights because they navigate using the moon. In nature, the moon is so far away that keeping a constant angle to its light helps them fly in a straight line. But when they try to do the same with a nearby light bulb, that strategy fails—so instead of flying straight, they spiral inward and end up circling the light, all disoriented and stuck.