Butterflies are insects of the order Lepidoptera. Lepidoptera comes from the Greek words lepidos (scale) and ptera (wing). The colored scales on their showy wings distinguish butterflies and moths from other insects. The coiled mouthpart, the proboscis, is another unique characteristic of butterflies and moths. Butterflies are thought to have evolved from moths. Moths existed before flowering plants, and butterflies evolved after in the late Cretaceous period. Most butterflies are active during the day (diurnal), and most moths are active at night (nocturnal). There are six families of butterflies: Swallowtails (Papilonidae), Whites and sulfurs (Pieridae), Brush-footed butterflies (Nymphalidae), Gossamer-winged (Lycaenidae), Metalmarks (Riodinidae), and Skippers (Hesperiidae).
There are a few possible origins of the name butterfly. One is that the common sulfur butterflies are a buttery yellow color. Another possibility may come from the Old Dutch word botershijte, meaning “butter poop.” This may have come from people observing that the butterfly when it first emerges from the chrysalis has fecal matter that is yellow or orange, or the tendency for butter-colored sulfur butterflies to feed on fecal matter. Another possible origin comes from a belief from the middle ages that butterflies stole milk and butter.
The life cycle of Lepidopterans has four stages: egg, caterpillar (larva), chrysalis (pupa), and adult (imago). Moths form a cocoon instead of a chrysalis for the pupa stage. The chrysalis is formed by hardening of the outer surface of the caterpillar, which separates from the body inside, similar to a snake shedding its skin. In contrast, moths build their cocoons using a glue-like substance produced by special glands.
Inside the chrysalis or cocoon, the caterpillar releases enzymes that dissolve the body tissues, but special groups of cells called imaginal discs remain. An imaginal disc for each adult butterfly is present at the egg stage. During metamorphosis, the protein-rich material from disintegrated caterpillar cells serves as fuel for rapid cell division to grow adult butterfly tissues.
What are the differences between butterflies and moths?
What's the difference between a moth and a butterfly? | BBC Science Focus Magazine