March 14: Moth Day

Today is Moth Day: A day to learn about and appreciate moths. Here are ten facts about moths:

1. Moths belong to the same family as Butterflies. There are about ten times as many species of moth as there are of butterfly, that is 160,000 species of moth in the world, many of which have yet to be described. Moths evolved long before butterflies, fossils having been found that may be 190 million years old.
2. How can you tell a moth from a butterfly? It can be tricky. While many moths are nocturnal, not all of them are. A fairly reliable way to tell is that butterflies have tiny clubs at the end of their antenna and moths don't.
3. Some adult moths never eat. Some drink nectar, but others have no mouth parts at all, such as the Luna moth. It lives for about a week and uses that time to mate and lay eggs. There are even some moths without wings - many females of the Tussock family don't have wings.
4. Male moths can detect as little as one molecule of female sex hormone from as much as seven miles/11km away.
5. The original bug in a computer programme was a moth. It got into a relay in Harvard on September 9, 1947 and caused the computer to break down. It was removed and taped to a log book, which is now at the Smithsonian National Museum of American History.
6. The biggest moth in the world is the Hercules moth, which lives in Australia. Its wingspan can reach 27cm. Thysania agrippina, native to South America, has a longer wingspan (up to 28cm/11in) but the Hercules moth's wings have the largest surface area of any insect (300square cm). At the other end of the scale is a yet to be described moth from the Democratic Republic of Congo, which was discovered in 2012. It’s only 1 mm long with a wingspan of 2 to 2.5 mm, ie about the size of a printed full stop.
7. The Hawk moth (Sphinx) is the world's fastest flying insect. It can reach speeds of over 50 kph.
8. Moths have been widely studied to help explain evolution, in particular the peppered moth. That's the one with pale and dark varieties. The light moths way outnumbered the dark ones before the industrial revolution, because they were camouflaged against light tree barks. When the trees became darkened by soot, the dark moths flourished because their lighter cousins started getting eaten because predators could now see them.
9. Moths have evolved numerous ways to prevent getting eaten. Some are masters of disguise, and look like less palatable insects, while others have evolved to look like twigs and even bird droppings. Other species have been found to react to ultrasound, and will fly lower when they hear it - to avoid being eaten by Bats. Tiger moths emit clicks which can foil bats' echolocation.
10. Like butterflies, moths need warmth in order to fly, but most have the problem that they can't bask in the sun at night. Instead, they warm themselves up by vibrating their wings, and have hairy bodies to trap the heat. Their hairiness makes them good pollinators. Moth-pollinated flowers tend to be fragrant and white, to allow moths to find them after dark.