About Butterflies and Moths – Part 4
By Mary Free, Extension Master Gardener
The shape, color, structure, and scent of a flower can determine the type of pollinators it attracts. A flower requires a pollinator that will visit it regularly and successfully transfer pollen in, or between, it and other flowers of its species to ensure fruit and seed production. For this service, animal pollinators usually receive a reward of food in the form of nectar or pollen or both.
Unlike bees that feed on both nectar and pollen, adult butterflies and moths visit flowers solely for the nectar. Exceptions are the neotropical Heliconius and Laparus butterflies that actively collect pollen grains with their proboscis (Hikl 2011). Because adult lepidopterans have no need for pollen, they lack specialized structures to transport it. Rather, in the course of obtaining nectar, their mouthparts, legs, or wings may brush up against sticky pollen grains, which they then carry from flower to flower as they feed.
Although lepidopterans are less effective in transferring pollen than bees, butterflies and numerous moths (e.g., mostly hawk, owlet, geometer, and yucca) are still important pollinators. Even if most are not a plant’s primary pollinator, lepidopterans may provide critical functional complementarity, a phenomenon that propounds that successful pollination of a plant increases when there is a greater diversity of pollinators. For example, research in cotton fields showed that butterflies and flies visited the plant’s outer flowers, which bees neglected, increasing flower visitations by 50 percent (Cusser et al. 2021).
Types of Flowers that Attract Butterflies
Many flowers with the same bright colors, including red and purple, and with narrow tubes and spurs that attract hummingbirds, also attract butterflies. Unlike hummingbirds that feed while hovering, butterflies perch or walk around as they feed, so they prefer flowers with wide landing platforms, such as composites like Echinacea and Rudbeckia (purple and orange coneflowers), Helianthus (sunflowers), and Symphyotrichum (e.g., blue wood aster and New England aster) or arranged in clusters like natives Asclepias (milkweed), Eutrochium (Joe-pye-weed), and Solidago (e.g., blue-stemmed goldenrod and rough-stemmed goldenrod). Besides providing nectar, some of these plants also host lepidopteran caterpillars. For example, Asclepias species are host plants for monarch caterpillars, as well as nectar plants for 31 of the 50 lepidopteran species in the table, Nectar and Host Plants for Selected Mid-Atlantic Butterflies and Moths, which will post tomorrow in Part 5.
BUTTERFLY GARDENING TIPS: Besides nectar and host plants, butterflies need:
1. refuge from wind and rain. Plant densely and shelter nectar flowers with fences, shrubs, or vines.
2. sun to warm their flight muscles when they are too cold to fly. As long as they can bask, butterflies will visit nectar flowers that are shaded during part of the day–so place a flat rock in a sunny spot nearby.
3. soil minerals for reproduction, which males extract by sipping moisture from mud puddles. To make a puddling area: place a shallow dish at ground level, fill it with sand mixed with yard soil and keep it damp.
Types of Flowers that Attract Moths
Flowers paler in color–dull red, purple, pink, or white–and stronger in scent attract moths. Fragrance is an important floral characteristic as moths process smells through two olfactory “channels”–one for their favorite flowers and the other for alternative nectar sources (Hines 2012). Some daytime bloomers, like Lonicera (honeysuckle) and Gardenia jasminoides (gardenia), emit more fragrance at night, while Petunia axillaris waits until nighttime to release a potent musty scent to entice moths. Flowers, like Oenothera caespitosa and O. biennis (evening primroses), Mirabilis jalapa (four o’clock), and Ipomoea alba (moonflower), open late afternoon or at night specifically to attract nocturnal pollinators.
Not all moths are nocturnal though; some, like hummingbird or bee-hawk moths, feed during the day or at dusk. Often mistaken for hummers due to their plump bodies, fan-like tails, audible hum, and flying movements, these moths hover to drink nectar from tubular flowers, unlike moths that perch and walk around on flower clusters to feed. When white-lined sphinx moths (Hyles lineata) fly “during the day they like brightly colored flowers but in the evening, they prefer white or pale-colored flowers, which are easier to see in the dark in contrast against green foliage” (Mahr 2022) and are more fragrant.
Native Nectar Plants
Nectar provides energy for adult lepidopterans while they mate and reproduce. While different lepidopterans are drawn to different plant species, native species are more likely to be most appealing and provide the quality nectar that native lepidopterans need. Native plants are also adapted to local climates and soil conditions and promote biodiversity. They are naturally more pest and disease resistant, meaning that they require little to no use of chemicals that can harm water quality and wildlife.
Left to right: Agastache foeniculum with eastern tiger and zebra swallowtails, cultivar Agastache foeniculum ‘Golden Jubilee,’ Echinacea purpurea with eastern tiger swallowtail, and cultivars Echinacea purpurea ‘Magnus’ with sachem skipper and two-spotted bumble bee and Echinacea purpurea ‘Pink Double Delight.’
Home improvement stores and many nurseries, though, tend to stock cultivars and hybrids (the genetic cross between two different species) instead of “straight” native species. Cultivars are bred to “enhance” the vigor or appearance of a particular species–improve disease/pest resistance, make it more compact, or alter foliage or flower color or form–sometimes to the detriment of nectar and pollen quality. Some ornamental cultivars have been proven to increase resistance to disease or to improve form without sacrificing their pollinator appeal, and in some cases, even increase pollinator visits by extending the bloom time. In fourteen direct comparisons of species and cultivars, a Pennsylvania State University study found that 50 percent of the time the species was better than the cultivar at attracting pollinators. It concluded that “it is not possible to generalize that the cultivar is better than or poorer than the species.”
However, some research has shown that for herbaceous plants, “the more manipulated the cultivars became, the less attractive they became to pollinators” (White 2013/2016). For example, native cultivar (or nativar) Agastache foeniculum ‘Golden Jubilee,’ with its compact form and chartreuse leaves, showed a marked decrease in lepidopteran visits compared to the straight native species. Likewise, lepidopterans showed significantly less interest in the yellow-flowered, highly fragrant hybrid Echinacea x ‘Sunrise’ and the pom-pom-like, double flowers of Echinacea purpurea ‘Pink Double Delight’ in which extra petals replaced reproductive parts than in the straight native species. From this and other research, there seems to be consensus about double-flowered varieties–that they are much more attractive to humans than to pollinators.
PATIO/BALCONY GARDENING TIP: In limited spaces, one might be tempted to go smaller–that is, to purchase compact cultivars. Although this might be a wise choice, compact cultivars can be less floriferous so consider the taller native species that takes advantage of the vertical space and provides more flowers per unit area. Also, to increase the impact of your space, choose nectar plants that are frequented by numerous lepidopteran species.
A Succession of Blooms
Allow for a succession of blooms from early spring to greet the first lepidopteran arrivals through fall to nourish the last departures. Even though most adult lepidopterans live for only a brief period, species differ in the timing of their life cycles and the number of generations in a season, so blooming flowers should be available for about nine months of the year. To help achieve this, add some non-native, non-invasive plants to supplement and complement native plant gardens.
Left to right: Gomphrena globosa with monarch, Lantana camara with silver-spotted skipper, Salvia with cabbage white, Verbena bonariensis with eastern tiger swallowtail, Hylotelephium ‘Herbstfreude’ AUTUMN JOY with common buckeye, Scabiosa ‘Butterfly Blue’ with orange sulphur, Zinnia with sachem skippers.
Native nectar plants that are herbaceous perennials expend a lot of energy developing their underground root systems often at the expense of flower production, reducing the duration of blooms. On the other hand, annuals–mostly non-natives–whose roots die at season’s end, can devote most of their resources to producing flower and seed. An annual’s extended bloom period ensures a continual nectar source for pollinators when native perennials have yet to flower or are in decline. Those that attract pollinators, such as Gomphrena globosa (globe amaranth), Lantana camara* (common lantana), Salvia, Verbena bonariensis (Argentinian vervain), and Zinnia, as well as many herbs and vegetables and some non-native perennials like Hylotelephium ‘Herbstfreude’ AUTUMN JOY (sedum), Salvia, and Scabiosa (pincushion) can serve as bridge plants, ensuring a constant supply of nectar. Also, spring bulbs, like Crocus, Galanthus (snowdrops), Muscari (grape hyacinth), wild type daffodils such as Narcissus jonquilla, and species-variety tulips, provide nectar while many perennials are still dormant. As with natives, use straight species or cultivars with proven track records of attracting pollinators, and avoid hybrids and double-flowers.
Lawns also can be attractive to pollinators not only for the grasses that can serve as host plants, but for “weeds” like Taraxacum (dandelions) and Trifolium (clover) that provide early season nectar. Adjust lawn mower blades to a height of 3 inches to ensure that dandelions and clover survive.
PLANTING TIP: To capture the attention of butterflies, who rely heavily on color when foraging, group three or more plants of the same species together in a mass rather than single plants of different species. Cut down on mulch, suppress weeds, and cool the soil by planting densely (follow the low end of spacing recommendations). Besides being aesthetically appealing, this allows pollinators to feed more efficiently and creates a shelter for them and other wildlife.
When female lepidopterans are ready to lay their eggs, they need to find a host plant on which their caterpillars can eat and grow. Though they may search for miles for such a plant, more butterflies will visit your garden for nectar when host plants for their caterpillars are nearby. Before choosing host plants for your landscape, especially trees, you may want to peruse your neighborhood to observe what large woody host plants are common–like oaks, maples, magnolias, and dogwoods–and then plant species that are less common. If space in the landscape is available and host plants are relatively small, consider planting more than one of the same species, and, for herbaceous perennials, which are also nectar plants, plant three or more of the same species. To attract monarch butterflies specifically, see Creating a Monarch Waystation, which will post Saturday in Part 6.
PATIO/BALCONY GARDENING TIP: In limited spaces, consider nectar plants that, for some lepidopteran species, do double duty as host plants such as Asclepias (milkweed), Ceanothus americanus (New Jersey tea), Sedum (stonecrop), Symphyotrichum (aster), Verbena, Vernonia (ironweed), and Viburnum.
As to native woody plant cultivars, experiments have shown that one characteristic in particular influences insect preference: those “selected to change green leaves to red, blue, or purple, either throughout the season or during leaf senescence in the fall, significantly reduce insect herbivory three- to five-fold” (Baisden et al. 2018). So for trees, shrubs, and vines, stick to cultivars that have the same leaf color as the straight native species.
PLANTING TIP: If you are concerned that defoliated plants will detract from your garden, then place host plants in more unobtrusive places, like the back of the border, where you do not need to remove dead foliage or flowers, which may harbor eggs or developing lepidopterans.
When choosing plants, make sure that they will thrive in the light, moisture, and soil conditions of your landscape. Consider how fast and how large they will grow–remember that even some native plants can spread aggressively. Consult field studies by botanical gardens or extension services to weigh the attributes of specific cultivars and their ability to attract pollinators. To observe native plant habit in a garden setting, visit the MGNV demonstrations gardens.
Before you purchase plants:
- Make sure that native wildflowers have been propagated in reputable nurseries and not harvested from the wild.
- Ask if plants were grown in a similar climatic region as your garden, and, even better, from local stock, in which case they would tend to be better adapted and increase the likelihood of not only surviving transplantation, but also thriving in your garden.
- Ask whether or not plants have been subjected to pesticides, especially systemic insecticides like Neonicotinoids, Butenolides, and Diamides, which are toxic to bees. In woody plants, these insecticides can reach high levels of concentration and remain for a longer period of time. Learn more about Buying Bee-Safe Plants.
- Find native plants sales and nurseries that produce natives (visit Plant NOVA Natives and the Virginia Native Plant Society).
PLANTING TIP: Try to create a natural and diverse habitat. The more diverse the vegetation in terms of species, shape, size (with horizontal and vertical layers) and seasonal interest, the more diverse the wildlife it will entice. In perennial/annual gardens, plan for three layers: tallest plants in the back of a rectangular border or in the middle of a circular design with low-growers in the front and and medium-growers in-between. Use the same three dimensional effect in containers with: “thrillers”–tall plant with upright habit in the back or center (if viewed from all sides) of the container, “fillers”–mounded plants in front or around the thriller, and “spillers”–trailing plants along the edge of the container.
Last but not least, to maintain an inviting habitat for butterflies, moths, and other pollinators, do NOT spray pesticides on or near nectar or host plants! Additionally, fungicides and herbicides might not only be harmful to pollinators, but the latter can kill plants on which they rely.
*Research shows that Lantana has an allelopathic effect, i.e., it releases biochemicals that can affect nearby plant life (Kato-Noguchi 2021). This is more likely to be a problem in places like Florida where Lantana has become invasive and is altering the plant community. If this is a concern, then growing it in a pot should mitigate adverse effects.
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References on Natives and Cultivars
- Aster. 2003-2005. Trial Garden. Mt. Cuba Center.
- Baisden EC. Tallamy DW. Narango DL. Boyle E. 2018. Do Cultivars of Native Plants Support Insect Herbivores? HortTechnology. 28(5). doi: 10.21273/HORTTECH03957-18
- Bees, Bugs & Blooms – A pollinator trial. Penn State. Center for Pollinator Research. Posted February 5, 2016. (includes best plants for number of pollinator visits and pollinator diversity)
- Calles-Torrez V. McGinnis EE. Laschkewitsch B. Hatterman-Valenti H. Knodel JJ. 2020. Pollinator Preferences for Selected Aster, False Indigo, Bee Balm and Sedum Flowers in North Dakota (H1962). North Dakota State University. (includes best cultivars for pollinator visitation, including butterflies)
- Coreopsis. 2012-2014. Trial Garden. Mt. Cuba Center. (includes information on pollinator visitation)
- Echinacea for the Mid-Atlantic Region. 2018-2020. Trial Garden. Mt. Cuba Center. (includes best echinacea for pollinators and info about butterfly visitation)
- Monarda. 2014-2016. Trial Garden. Mt. Cuba Center. (includes best monarda for butterflies and moths)
- Phlox for Sun. 2015-2017. Trial Garden. Mt. Cuba Center. (includes best phlox for butterflies)
- Phlox for Shade. 2015-2017. Trial Garden. Mt. Cuba Center. (includes best phlox for butterflies)
- White AS. From Nursery to Nature: Are native cultivars as valuable to pollinators as native species? Posted by pollinatorgardens February 8, 2013; updated 2016.
- White AS. 2016. From Nursery to Nature: Evaluating Herbaceous Flowering Plants Versus Native Cultivars for Pollinator Habitat Restoration. PhD dissertation, University of Vermont.
- Alabama Butterfly Atlas © 2022 – Butterfly Atlas, USF Water Institute, University of South Florida (accessed June 1–5, 2022)
- Butterflies/Moths – Lepidoptera Family. Montana Field Guide. Montana Natural Heritage Program. (accessed May 1–3, 2022)
- Carman D. 2017. Butterfly Larval Host Plant List. Master Gardener Program. PennState Extension. (accessed April 27 2022).
- Cusser S, Haddad NM, Jha S. July 2021. Unexpected functional complementarity from non-bee pollinators enhances cotton yield. Agriculture, Ecosystems & Environment. 314(11):107415. ISSN 0167-8809, doi: 10.1016/j.agee.2021.107415.
- Free M. 2013. Creating Inviting Habitats For the Birds, Butterflies & Hummingbirds. Virginia Cooperative Extension.
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- Kondo M, Oyama-Okubo N, Ando T, Marchesi E, Nakayama M. 2006. Floral scent diversity is differently expressed in emitted and endogenous components in Petunia axillaris lines. Ann Bot. 98(6): 1253-1259. doi:10.1093/aob/mcl212.
- Mahr S. White-lined Sphinx Moth, Hyles lineata. Wisconsin Horticulture. University of Wisconsin-Madison. (accessed May 26, 2022)
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- Stokstad E. 2021. Butterflies provide ‘extraordinary’ help pollinating cotton fields By visiting flowers that bees don’t, butterflies and flies add significantly to harvests. Science. doi: 10.1126/science.abi9757.
- Wagner D. 2005. Caterpillars of Eastern North America. Princeton University Press. ISBN: 0-691-12144-3.