Nocturnal Enchanters: All About Luna Moths

Wednesday, July 28, 2021
The word 'moth' doesn't always conjure the same feelings or thoughts as the word 'butterfly'. Moths are typically thought of as dull creatures, living in the darkness and flying into porch lights repeatedly, whereas butterflies are thought of as beautiful, elegant, and delicate pollinators. But the moth world is anything but dull, and if you've ever seen the enchanting green glow of the Luna Moth, you will surely agree. 

Luna Moth, adult female

It is nearly impossible to mistake a Luna Moth (Actias luna) for any other moth or butterfly species found in Ontario due to their many unique characteristics. As adults, Luna Moths have a nearly 12cm wingspan (with some even reaching up to 17cm!), with long and curving tails on their hindwings that trail 6cm. Their overall wing colouring is pale to lime green, with brown, pink, or yellow wing edging, and transparent eyespots on each of their four wings, with the forewing eyespots joined to the wing edging by a dark line. The abdomen is white in colour and clothed in thick "fur", with six pink to brown legs. Though the fuzzy white hairs on the abdomen do look very similar to fur that you find on mammals, they are actually fluffy scales used in the same way as fur, to help insulate the body. The face of the Luna Moth is very pixie-like in appearance, with an angular structure, two large black eyes, and a set of feathery yellow antennae. Both male and female Luna Moths are similar in appearance, but do display some sexual dimorphism which can be noted in their antennae; males have wider, more prominent antennae, whereas females' are less pronounced (the individual pictured here is a female). Males use their robust antennae to detect pheromones emitted by females, which they are able to track over 1km away.

Habitat & range
Luna Moths are found throughout Canada, the United States, and northern Mexico. In Ontario, their range extends to many parts of the province including southern, central, and as far north as James Bay. Luna Moths can be found in forested areas heavily populated with their larval host plants walnut, willow, maple, birch, cherry, butternut, oak, or elm. While their larvae feed on tree leaves, adult Luna Moths do not feed at all, living only long enough to reproduce and lay eggs. Like all moth species, Luna Moths are attracted to artificial outdoor lights such as porch lights or streetlights, and can sometimes be seen fluttering around them. 

Luna Moth larvae - Photo courtesy of Ann Brokelman

Life cycle

    As adults, Luna Moths do not feed - in fact, they don't even have mouth parts that would allow for them to do so. Female Luna Moths' sole purpose is to reproduce and lay eggs, and in her short week-long lifespan, she will lay an average of 200 eggs in small clusters on leaves of host plants. Once she is finished laying, the female gradually weakens and dies. After approximately 10 days of laying, surviving and viable eggs hatch into caterpillars.

    Luna Moth caterpillars are bright green with short hairs on each body segment, thin yellow stripes on either side, small red knobs or bumps, and a green or brown head. Larvae feed on host plant leaves (mentioned above), and after about a week, moult or shed their skin. Luna Moth caterpillars go through a total of five larval stages, known as instars, until they reach a length of 8cm. Once they've reached their maximum length, larvae will enter the pupal stage.

    This is where the magic happens! To get the process started, Luna Moth caterpillars drop to the forest floor where they will create their cocoons. Caterpillars will then choose a nearby leaf (or multiple) that will be used as material to wrap and camouflage themselves for this important life stage. Using their spinnerets, caterpillars spin silk around the leaf and their bodies until a cocoon is formed. They will remain on the ground in their cocoons until their transformation to adult moth is complete. This process can take anywhere from two to three weeks depending on weather conditions. 

    Once emerged from their cocoons, Luna Moths must take time to let their wings fill with blood before taking their first flight. They do this by crawling to and climbing a nearby tree to rest. During this time they will slowly flap their wings up and down to help increase blood flow. This is a very vulnerable time for moths, as they cannot flee if predators approach. Once this process is completed, Luna Moths are ready to take flight in search of a mate. Flight time in Ontario lasts from May to July. 

Luna Moth, adult female

Three simple steps for creating a moth-friendly yard

  1. Plant host species and go pesticide-free: Walnut, willow, maple, birch, cherry, butternut, oak, and elm, are just some of the native host plants Luna Moth larvae feed on. These plant species are also used as foodplants and habitat by many other beneficial insect species, birds, mammals, and herptiles. In addition to planting host species, opting to go pesticide free in your yard will help save thousands of wild lives, and increase biodiversity in your own backyard. 

  2. Avoid using outdoor lighting: Outdoor lighting is a big draw for moths and other nocturnal creatures. Moths have evolved to travel by the light of the moon and often become disoriented by artificial lighting, hindering their navigational abilities and causing them to fly around lights where they are vulnerable to predators, or die due to exhaustion. To help moths fulfil their nocturnal destinies, avoid using outdoor lighting as much as possible. 

  3. Leave the leaves: There are so many reasons to leave the leaves in the fall - and moths are one of them! Many moth species, including Luna Moths, spend their pupal stage on the ground, wrapped in leaves where they are well camouflaged from predators looking for a snack. Unfortunately, they aren't safe from lawnmowers, leaf blowers, or mulchers down there, and many die each year due to unnecessary yard work. If you must rake in your yard, opt to keep a leaf pile instead of bagging or mulching to allow for the creatures hidden within a chance at reproducing and contributing their genes to the next generation. Who likes yardwork anyway?

Happy trails!
- Shayna 

1 comment: