Moths get called the lesser butterfly. Dustier, browner, out at the wrong hour. This is unfair on several counts, starting with the numbers: there are roughly ten times more moth species than butterfly species. The night shift is the main shift.
Moth versus butterfly
The honest differences are small. Moths tend to have feathery or threadlike antennae; butterflies carry little clubs on the ends of theirs. Moths mostly rest with wings flat or tented; butterflies fold them upright. Moths mostly work at night. Every one of these rules has exceptions, which is very like the night shift — hard to pin down on purpose.
Why do moths fly to the light?
The old explanation said moths navigate by the moon, holding it at a fixed angle, and a porch light breaks the compass. The newer research — high-speed cameras on moths around artificial lights — found something stranger: flying insects keep the brightest part of the sky at their backs to know which way is up. A lamp convinces the moth that up is wherever the bulb is. So it tilts, and banks, and circles — not drawn to the flame, just trying to keep a false sky overhead.
The reflex has a name: the dorsal light response. It is the same mechanism that keeps an insect the right way up over open ground, working exactly as designed, against a light source that evolution never had to account for.
It is not desire. It is a navigation error that looks like devotion. There is probably a lesson in that, which we decline to spell out.
Why is a moth flying in circles around a light?
The circling is the visible part of the error. Because the moth is trying to keep the brightest thing at its back, a lamp at head height makes it roll and tilt to put that glow overhead. Correcting again, and again, bends the flight path into a shallow orbit around the bulb, which is why the moth appears to circle instead of landing. The high-speed footage recorded the rest of the sequence too: orbiting, then stalling with the wings still beating, then in some cases turning upside down and dropping.
A candle works the same way. A flame is only a small, very bright point source, so an insect caught in its orbit is not seeking the fire; it is failing to find the sky. Switch the lamp off, or shield it so the light throws downward, and the insect usually moves on within a minute or two. It was never coming for you.
What the folklore says
This part is belief, not biology — but it is old and widespread belief. In parts of Britain and Ireland, a white moth entering the house was said to be a soul visiting — or leaving. The death's-head hawkmoth, with its skull-marked back, was read as an omen wherever it landed. In Mexican and Caribbean tradition, the large black witch moth carries a similar reputation; in some tellings a death follows its visit, in others, luck.
A creature that appears from the dark, lands on the lit window, and watches — it was never going to escape symbolism.
One more field note
The luna moth, palest and most ghostlike of the lot, emerges without functional mouthparts. It does not eat. It lives about a week, on whatever it gathered as a caterpillar, and spends that week looking for another luna moth. Draw your own conclusions about priorities.
From the archive
The founding thesis is stated plainly on the Moths Are Just Goth Butterflies specimen. The dedicated Moth and Bat Shirts file gathers the nocturnal flyers in one place. The wider night shift, including the plants that poison politely, is kept in the Night Garden.