By Leah Brooks, Marketing Coordinator at Mt. Cuba Center
Happy National Moth Week!
While there are many gorgeous and interesting moths that call Mt. Cuba Center home, those in the silk moth family Saturniidae are among the most charismatic. Members of this group are commonly referred to as Saturniids and include beauties such as the Luna moth, imperial moth, and regal moth. Read on to learn about the life cycles of these moths and how you can support them in your landscape!
Luna moth (Actias luna)
The Luna moth (Actias luna) is known for its distinctive pale green wings and long, elegant tails. If you see one, count yourself lucky, as these breathtaking beauties only live for about a week! During that period, they eat nothing, relying instead on energy stored in their bodies, as they search for a mate. Like all mature Saturniids, adult Luna moths have only vestigial (non-functioning) mouthparts. Since Saturniids don’t visit flowers for nectar, they don’t transport pollen. Thus, some of the showiest moths are not pollinators at all!
A cute fluffy face-but no mouth!
Although mature Saturniids don’t eat, during the larval stage they consume the leaves of various native trees and shrubs. As with many Lepidopterans (moths and butterflies), luna moth larvae depend on specific host plants for their food. Some of their host plants include trees like white oak (Quercus alba), hickory (Carya spp.), red maple (Acer rubrum), and river birch (Betula nigra). By incorporating these native trees into your landscape, you provide essential resources for Luna moths and contribute to the biodiversity and conservation of our native ecosystems.
A Luna moth caterpillar. At this size, pupation is not far away!
When a Luna moth caterpillar reaches a delightfully chunky size, it crawls from its host plant to the ground. If the caterpillar is lucky, it will find a “soft landing” waiting for it. A soft landing is a diverse native planting around the trunk of a native tree that protects the health of the tree in addition to providing many insects with a safe place to carry out their life cycles. Once on the ground, the Luna moth caterpillar incorporates dead leaves (an important component of a soft landing) into its silk cocoon.
There, in the cover of the soft landing, protected by the camouflage of its cocoon, the Luna moth pupa undergoes a transformation. This pupal stage usually lasts 2 weeks, but if the metamorphosis happens late in the season, the pupa will overwinter in the cocoon. When the moth emerges from the cocoon, it must allow its wings to dry and harden for 2-3 hours. It is during this time, while the moths hang motionless from a surface or object, that they are most frequently noticed by humans.
A Luna moth waiting for its wings to dry and harden.
The preceding scenario assumes that the luna moth caterpillar was lucky enough to survive to adulthood, avoiding the various dangers that pose a threat to larvae in a maintained landscape. If the caterpillar had descended the tree and pupated in an area that was routinely mowed, or in a bed that was cleared of dead leaves, there is a much lower chance that it would have been able to successfully complete its life cycle. In natural landscapes, the leafy camouflage of the cocoon serves to protect the pupa as it rests in the surrounding leaf litter. However, with the common landscape practice of leaf removal and disposal, the camouflage is actually a detriment to the moth’s survival in human spaces. Many pupae are thrown away, burned, mulched or otherwise destroyed with the rest of the leaf litter. To avoid this, rake leaves into garden beds where they will break down into important nutrients that enrich your soil. Creating soft landings (or at least raising the height of mower blades under trees) and leaving the leaves are easy and impactful ways that gardeners can help larvae in their landscapes.
Regal moth (Citheronia regalis)
Most Saturniid larva spin a silken cocoon in the leaves of a preferred host plant, in leaf litter on the ground, or in crevices of rocks and logs. Some species, like the imperial moth (Eacles imperialis) and regal moth (Citheronia regalis), descend from their host plants and burrow under the soil. There, they pupate in a small chamber, without a cocoon or other protective covering. To support moths and other insects that pupate underground, avoid the use of landscape fabric and other barriers that prevent larvae from burrowing into the soil.
You can do your part to ensure that these enchanting moths are around for many Moth Weeks to come by trying some of these tips and educating others about landscaping practices that benefit or harm our native caterpillars!