You’ve seen them after dark bouncing around the porch light — intricately patterned wings like falling leaves fluttering over your screen door. Or you’ve sat in a garden and followed their lazy, colorful flight from flower to flower.  Lepidoptera includes all known species of moths and butterflies — the only insects with wings covered in microscopic scales. Moths have traditionally been the victims of bad press: ugly wool-ruiners, symbols of darkness (thanks, Silence of the Lambs)... In reality, moths vary immensely in color, shape, and lifespan. Sharing a common ancestor, moths and butterflies are evolutionarily extremely close. Moths aren’t just around as a treat for bats and birds, either. Both the colorful butterfly and their goth cousin act as important pollinators. So, what are the differences, and how do you encourage these ephemeral insects to appear in your garden? 

Almost every organism’s appearance serves the ultimate evolutionary purposes — staying alive and reproducing. Moths, generally night-flyers, sport wings of brown or black often patterned after tree bark. These colors camouflage them during the day, and further obscure them at night. Moths cozy up to a tree or leaf pile, unfurl their wings and sleep peacefully knowing potential predators look right past them. Day-flying moths (yes, that’s a thing!) use different strategies to avoid predators. Like butterflies, they sport bright colors to warn of toxicity or mimic other insects and animals that predators find distasteful. The hummingbird clearwing moth famously disguises itself as — you guessed it — a ruby-throated hummingbird, with stunning red accents. 

Butterflies' wild patterns similarly warn predators away or camouflage them among bright flowers. The tiny scales on butterfly wings reflect light, creating an iridescent shine. Beyond what the human eye can see, these scales form layered spots and reflections only visible to the more sensitive eyes of reptiles and birds. Some species, such as the blue morpho butterfly of Central and South America, use their brightly colored wings in mating rituals. Butterflies usually rest with their wings folded, while moths hold their wings open. 

Unfortunately, Lepidoptera haven’t discovered Tinder yet. Instead, they use their sense of smell. The unique, feathery antennae of moths serve as their ‘nose’, picking up the scents of predators, food, and most importantly, pheromones of other moths ready to mate. Male moths can detect a willing female from miles away. The antenna’s structure helps to filter out dust and other pollutants, and trap pheromones. 

Butterfly antennae are club-shaped — a thin strand with small rounded ‘clubs’ on the end. Apart from detecting pheromones, these clubs help butterflies measure air temperature and pressure, which tells them when to migrate or hibernate. Butterfly hibernation is called diapause. The butterfly or caterpillar will eat fatty foods to build up an energy store, and then slow its metabolism. Once more food is available and the weather warms up, they’ll get right back to their daily routine.

Both moths and butterflies begin life as caterpillars. (In fact, it’s moth caterpillars that ruin your wool.) After a couple weeks of an all-you-can-eat plant buffet, caterpillars begin their transformation. Moth pupae generally molt within woven silk cocoons, though some burrow underground to metamorphose. A butterfly caterpillar forms a hard, shiny exoskeleton, the chrysalis, and, after transforming, sheds it. 

In short, moths generally fly at night, have fronded antenna and a fuzzy body, form a cocoon, and rest with their wings extended. Butterflies are day fliers, have club-shaped antennae, form a chrysalis, and rest with their wings closed. Although there are a lot of exceptions, moths’ wings are generally darker than butterflies’. 

The Lepidoptera order is one of the largest pollinator groups, next to bees and flower flies. The combined effort of diurnal butterflies and nocturnal moths reaches a variety of plants, including many vegetables and herbs. Unfortunately, both moth and butterfly populations are decreasing across the U.S., largely due to habitat loss, pesticides, and agricultural intensification — which strips the land of varied wild species. Light pollution often disrupts the reproduction of Lepidoptera, especially moths, and makes them more visible to predators. So, what can we do?

Small areas of land, like roadsides and city parks, have the potential to support butterfly and moth populations. Planting a variety of native plant species, especially wildflowers, can be extremely beneficial to pollinators. Replacing white outdoor lighting with softer, yellow lights lessens disruptions of night-flying insects. If you’re interested in starting a pollinator garden or expanding your own, check out the Pennsylvania Department of Conservation and Natural Resources website: www.dcnr.pa.gov. Under their “Wild Plants” page, you can find lists of native plants, where to buy them, and even garden templates! If you’re in for a more expansive read, the DCNR published their “Pollinator Conservation Plan” for the state of Pennsylvania, which contains tons of information on threats to pollinators and how to maintain their habitat specifically tailored to Pennsylvania. Want to see an example of a pollinator garden in person? The Haverford Arboretum’s Pollinator Garden is growing around the duck pond! Now, get outside and start practicing your moth and butterfly identification skills. 

References:

https://www.si.edu/spotlight/buginfo/moths

https://www.sciencefocus.com/nature/whats-the-difference-between-a-moth-and-a-butterfly/

https://www.chesapeakebay.net/news/blog/moths_pick_up_the_night_shift

https://www.nationalgeographic.com/animals/article/150307-butterflies-caterpillars-colors-predators-prey-animals-science

https://phys.org/news/2014-06-dna-analysis-reveals-butterfly-moth.html

https://bugunderglass.com/butterfly-migration-and-diapause/ 

http://blog.umd.edu/agronomynews/2020/06/05/moths-butterflies-and-pollination/