Butterfly gardening is a way to create, improve, and maintain habitat for lepidopterans including butterflies, skippers, and moths.[2] Butterflies have four distinct life stages—egg, larva, chrysalis, and adult. In order to support and sustain butterfly populations, an ideal butterfly garden contains habitat for each life stage.
As adults, butterflies feed mainly on nectar, but they have also evolved to consume rotting fruit, tree sap, and even carrion.[6] Supporting nectarivorous adult butterflies involves planting nectar plants of different heights, color, and bloom times. Butterfly bait stations can easily be made to provide a food source for species that prefer fruit and sap. In addition to food sources, windbreaks in the form of trees and shrubs shelter butterflies and can provide larval food and overwintering grounds.[7] "Puddling" is a behavior generally done by male butterflies in which they gather to drink nutrients and water and incorporating a puddling ground for butterflies will enhance a butterfly garden.[8][9] While butterflies are not the only pollinators, creating butterfly habitat also creates habitat for bees, beetles, flies, and other pollinators.[7]
Butterfly gardening provides a recreational activity to view butterflies interacting with the environment. Besides anthropocentric values of butterfly gardening, creating habitat reduces the impacts of habitat fragmentation and degradation. Habitat degradation is a multivariate issue; development, increased use of pesticides and herbicides, woody encroachment, and non-native plants are contributing factors to the decline in butterfly and pollinator habitat.[10] Pollination is one ecological service butterflies provide; about 90% of flowering plants and 35% of crops rely on animal pollination.[10][11] Butterfly gardens and monarch waystations, even in developed urban areas, provide habitat[12] that increases the diversity of butterflies and other pollinators, including bees, flies, and beetles.[13]
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Before buying plants and digging into the soil, "ground-truthing" is a necessary first step, Ground-truthing involves surveying a property in order to assess the current resources available. Some aspects to keep in mind are the following:
south-facing slopes
natural wind breaks
present plant species
present butterfly species
Butterflies are ectothermic and rely on solar radiation for their metabolism. South-facing slopes are an ideal location for a butterfly garden, as they provide the most solar radiation (in the Northern Hemisphere; the opposite is true in the Southern Hemisphere). Shrubs and trees provide wind breaks for butterflies, and can also be host plants, such as spicebush (Lindera benzoin) or pawpaw (Asimina triloba).[14][15]
The types of plants used in a butterfly garden will determine which species of butterflies will visit a garden. Lepidoptera societies and the Department of Natural Resources often provide state and county distribution maps of local butterflies. There are lists of butterfly species and their host plants which are informative to the plant species needed in the garden (see: Larval food plants of Lepidoptera). While non-native plants do provide flora resources later in the season, they can have an overall negative effect on butterflies and other pollinators.[10] Therefore, it is often recommended to use native plants.
Avoid cultivars of plants that have "double flowers" as their reproductive parts have been converted into extra petals and therefore do not produce floral rewards for butterflies and other pollinators.[18] Care should also be taken to research a species to assure that it is not invasive in a given region.
Buddleja davidii, which is often called "butterfly-bush", attracts many butterflies.[19] As it originated in China, it is presently planted in many parts of the world in which it is non-native.[19] In such settings, the plant feeds many native butterflies and other adult pollinators, but not many of their larvae.[20] As B. davidii is invasive in some areas, plantings of the species are controversial.[20][21] To prevent seeding and to promote further flowering, its blossoms need to be removed ("deadheaded") as soon as they are spent.[19]
A number of Buddleja cultivars have become available that have a variety of sizes and blossom colors. University studies have suggested that nectaring butterflies have greater preferences for some of these than for others, with Lo & Behold 'Blue Chip' and 'Pink Delight' heading a list of eleven.[22]
Some Buddleja cultivars are either sterile or produce less than 2% viable seed (see "Non-invasive" Buddleja cultivars).[19][20][23][24] The state of Oregon, which designates B. davidii as a "noxious weed" and initially prohibited entry, transport, purchase, sale or propagation of all of its varieties, amended its quarantine in 2009 to permit those cultivars when approved or when proven to be interspecific hybrids.[19][20][23][25]Monarch Watch recommends planting only male-sterile "Flutterby" cultivars.[26]
It is important to avoid purchasing plants and seeds treated with insecticides such as neonicotinoids. Although not yet conclusive, there is increasing evidence that neonicotinoids can have negative effects on pollinating insects, including butterflies.[27]
"Puddling" refers to the behavior of male butterflies congregating on wet soil, dung, and carrion to feed on nutrients, specifically sodium.[8] Nectar is low in sodium, and sodium is a limiting nutrient for Lepidoptera. Male butterflies are able to transfer sodium to females during copulation. The sodium is passed onto offspring and increases reproductive success.[9] To create a simple puddling habitat, fill a shallow dish (like a draining tray for a pot) with wet sand. To increase the nutrients, mix compost with the sand. Add footholds for butterflies by adding different sized rocks.
There are numerous recipes for creating butterfly bait, but they have common ingredients. Fermentation is the key to a good bait, as it mimics the fermentation of rotting fruit and sap in the natural environment.[28] Recipes include blending rotten fruit (i.e. bananas) with beer, maple syrup, molasses, or sugar. Often yeast is added as well to the mixture and left to ferment for a week. Urine is also known to attract fruit-feeding butterflies.[29] The bait can be laid on stumps, rocks, and tree limbs.
This section needs additional citations for verification. (July 2021)
In the absence of pesticides, aphids and true bugs may infest plants. Some gardeners may wish to release ladybugs (ladybirds) and other biological pest control agents that do not harm butterflies in order to control aphids. However, the release of ladybugs is not a good idea in places such as the United States where the species that is released is generally the invasive Chinese ladybug.
An alternative to this is to wait for local predatory insects to find the aphids. One technique some use to quicken this process if the infestation is particularly high is to spray the bushes with a mix of sugar and water, simulating aphid honeydew. This is known to attract lacewings whose larva eat aphids.[30]
Another method of control is by spraying the plants with water, or rinsing plants with a mild dish detergent/water solution (although caterpillars should be relocated before suds are applied). Scented detergents are fine; those containing OxiClean should be avoided. The aphids will turn black within a day, and eventually fall off. One last technique is to plant a variety of different flowers, including ones that attract hoverflies and parasitic Braconid wasps, whose larvae kill pest species. Still, it is not advisable to kill all aphids, just to control them so that they are not detrimental to plants. Aphids still play a role in the environment by providing food for predators. There are even some caterpillars such as the harvester which only eat certain aphid species instead of plants.[31]
With small home butterfly gardens, it is common for the larvae to exhaust the food source before metamorphosis occurs. Gardeners of monarch butterflies can replace the expended milkweed with a slice of pumpkin or cucumber, which can serve as a substitute source of food for monarch caterpillars in their final (fifth) instar.[32] Planting multiple plants in clumps can help lower the chances of running out of leaves.
Monarch Watch provides information on rearing monarchs and their host plants.[33] Efforts to restore falling butterfly populations by establishing butterfly gardens and migrating monarch "waystations" require particular attention to the target species' food preferences and population cycles, as well to the conditions needed to propagate and maintain their food plants.[34]
For instance, it has been suggested that the commonly sold, popular Brazilian (or tropical) milkweed (Asclepias curassavica) is problematic; although it successfully beckons the butterflies to lay their eggs, with gardeners often finding a veritable caterpillar "nursery" on their plants, the particular species in question is native to South America. This can be potentially altering to the butterflies' natural migratory instinct, to fly and breed south of the United States; they become "spoiled" on garden tropical milkweed, stay where they are, and potentially avoid breeding.
Awareness of different milkweed species is of vital importance. For example, in the Washington, DC, area and elsewhere in the northeastern and midwestern United States, common milkweed (Asclepias syriaca) is among the most important food plants for monarch caterpillars,[35] especially when its foliage is soft and fresh. As monarch reproduction in that area peaks in late summer, when most A. syriaca leaves are old and tough, the plant needs to be cut back in June, July, or August, to assure that it will be regrowing rapidly, when monarch reproduction reaches its peak. Similar conditions exist for showy milkweed (A. speciosa) in Michigan and for green antelopehorn milkweed (A. viridis) where it grows in the southern Great Plains and the western United States.[36] In addition, the seeds of A. syriaca and some other milkweeds need periods of cold treatment (cold stratification) before they will germinate.[37]
To protect seeds from washing away during heavy rains and from seed-eating birds, one can cover the seeds with a light fabric or with an 0.5in (13mm) layer of straw mulch.[38] However, mulch acts as an insulator. Thicker layers of mulch can prevent seeds from germinating if they prevent soil temperatures from rising enough when winter ends. Further, few seedlings can push through a thick layer of mulch.[39]
Many species of milkweed contain toxic cardiac glycosides (cardenolides). Monarch caterpillars deter predators by incorporating these chemical compounds into their bodies, where the toxins remain throughout the insect's lifetime.[40] Although monarch caterpillars will feed on butterfly weed (A. tuberosa) in butterfly gardens, it is typically not a heavily used host plant for the species.[41] The plant contains only low levels of cardiac glycosides. This may make A. tuberosa unattractive to egg-laying monarchs.[42] Some other milkweeds have similar characteristics.[43]
A. tuberosa also has rough leaves and a layer of trichomes, which may inhibit oviposition or decrease a female's ability to sense leaf chemicals.[44][45] As a result of these factors, reproducing monarchs lay fewer eggs on A. tuberosa than they do on most other milkweeds.[44][41] While the plant's colorful flowers provide nectar for many adult butterflies, A. tuberosa may therefore be less suitable for use in butterfly gardens and monarch waystations than are other milkweed species.[44]
Breeding monarchs prefer to lay eggs on swamp milkweed (A. incarnata).[46]A. incarnata is therefore often planted in butterfly gardens and "Monarch Waystations" to help sustain the butterfly's populations.[47][48]
However, A. incarnata is an early successional plant that usually grows at the margins of wetlands and in seasonally flooded areas. The plant is slow to spread via seeds, does not spread by runners and tends to disappear as vegetative densities increase and habitats dry out.[49] Although A. incarnata plants can survive for up to 20 years, most live only two-five years in gardens. The species is not shade-tolerant and is not a good vegetative competitor.[49]
Brower, Lincoln P.; Taylor, Orley R.; Williams, Ernest H.; Slayback, Daniel A.; Zubieta, Raul R.; Ramírez, M. Isabel (March 2012). "Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk?: Decline of monarch butterflies in Mexico". Insect Conservation and Diversity. 5 (2): 95–100. doi:10.1111/j.1752-4598.2011.00142.x. hdl:2060/20140010155. S2CID86566051.
Ômura, Hisashi; Honda, Keiichi (November 2003). "Feeding responses of adult butterflies, Nymphalis xanthomelas, Kaniska canace and Vanessa indica, to components in tree sap and rotting fruits: synergistic effects of ethanol and acetic acid on sugar responsiveness". Journal of Insect Physiology. 49 (11): 1031–1038. Bibcode:2003JInsP..49.1031O. doi:10.1016/j.jinsphys.2003.07.001. PMID14568581.
United States Department of Agriculture (December 2022). "Maryland Conservation Planting Guide"(PDF). Mix 16: High Diversity Native Grass/Forb Mix for Mesic Sites. p.19. Archived(PDF) from the original on January 6, 2024. This mix has a predominant wildflower component for optimum wildlife and pollinator habitat.
Carlton, Marc; Bostock, Helen. Head, Steve (ed.). "Plants for Pollinators". United Kingdom: Wildlife Gardening Forum. Archived from the original on July 30, 2021. Retrieved August 1, 2021. 'Double' or flora pleno flowers have been bred so that most, or all, of the reproductive parts of the flower have been converted into extra petals, so are useless for pollinators.
Dhuill, E.N.; Smyth, N. (2021). "Invasive non-native and alien garden escape plant species on the southern cliffs of Howth, Co. Dublin (H21)". Irish Naturalists' Journal. 37 (2): 102–108.
"Neonicinoid Pesticides — The Facts". Neonicotinoid Pesticides & Bee Colonies. Compound Interest: Explorations of everyday chemical compounds. April 2015. Archived from the original on August 2, 2021. Retrieved August 2, 2021. Can accumulate in soil; low concentrations found in nectar of treated crops. .... Negative impacts on monarch butterly populations in the USA have recently been suggested.
National Academies of Sciences, Engineering, and Medicine (2020). Evaluating the Suitability of Roadway Corridors for Use by Monarch Butterflies. Washington, D.C.: National Academies Press. pp.79–80. doi:10.17226/25693. ISBN9780309481328. LCCN2020935714. OCLC1229163481. S2CID218854539. National Cooperative Highway Research Program (NCRHP) Research Report 942. Archived from the original on July 29, 2020. Retrieved July 8, 2021. Could roadside mowing stimulate milkweed growth and support monarch breeding? Limited research in eastern North America has shown that spring or summer mowing can promote new growth and extend the availability of milkweed plants for monarch breeding. Mowing may stimulate growth of some milkweed species, particularly those that spread through rhizomes like common milkweed (A. syriaca) and showy milkweed (A. speciosa). Summer (June or July) mowing in Michigan resulted in more monarch eggs on regenerated stems than unmowed stems. Summer (July) mowing and burning can increase green antelopehorn milkweed (A. viridis) availability in the late summer and early fall in the Southern Great Plains, whereas in areas without mowing, the milkweed has senesced by August. In the West, showy milkweed will regrow after summer mowing and continue to support monarch breeding (Stephanie McKnight, personal observation). However, more research is needed in other areas to determine the optimal timing and frequency of mowing that promotes not only milkweed but also nectar plants. It is also unknown if the benefit of additional milkweed availability in the fall outweighs the costs of the larval mortality caused by summer mowing. The benefits are likely greater in areas that primarily have breeding monarchs in the spring and fall and where the dominant species of milkweed spread by rhizomes. Sources: Alcock et al. 2016; Baum and Mueller, 2015; Bhowick 1994; Haan and Landis 2019; Fischer et al. 2015{{cite book}}: CS1 maint: multiple names: authors list (link)
Higgins, Adrian (May 27, 2015). "A gardener's guide to saving the monarch". Home & Garden. The Washington Post. Archived from the original on May 31, 2015. Retrieved October 17, 2020. 'The monarch doesn't care where the milkweed grows, and putting it in residential neighborhoods makes perfect sense,' said Doug Tallamy, an entomologist at the University of Delaware, author and expert on wildlife habitat gardens. .... The Smithsonian Institution's Butterfly Habitat Garden .... and the Ripley Garden .... are both good places to see milkweed integrated into a garden setting. At the butterfly garden, you can see the common milkweed ... now looking pretty good in fresh, unblemished clumps. By late summer, it looks tall, tired and tough. Tallamy says if you grow it, you should cut it back at least by half in June to produce soft foliage in late summer that will be more munchable for the caterpillars. If you do that, make sure there are no larvae on the plant before you chop it.
Abugattas, Alonzo (January 3, 2017). "Monarch Way Stations". Capital Naturalist. Archived from the original on March 8, 2021. Retrieved July 5, 2021– via Blogger. Virginia is blessed for instance with 13 native Asclepias species plus 4 climbing vines that Monarch caterpillars can feed on. For the best results, cut the some of the stems back in late summer after they've bloomed. Fall is the when we get the most Monarchs laying eggs on our milkweeds. Since the mother butterflies prefer young, more tender growth, you can provide this by timing your pruning so there are new leaves by September or so for the arriving Monarchs. Just make sure to leave a few to produce pods for seeds. The local monarch favorite is Common Milkweed (A. syriaca), .....
Gomez, Tony. "Asclepias syriaca: Common Milkweed for Monarch Caterpillars". Monarch Butterfly Garden. MonarchButterflyGarden.net. Archived from the original on March 16, 2015. Retrieved October 17, 2010. Cut- At mid season after the blooms have faded, cut some common plants back by about a third. This promotes fresh plant growth and could get you an extra generation of monarchs on the fresh new leaves. Leave some plants uncut if you want to harvest milkweed seeds in fall.
Landis, Thomas D.; Dumroese, R. Kasten (2015). "Propagating Native Milkweeds for Restoring Monarch Butterfly Habitat"(PDF). International Plant Propagators' Society, Combined Proceedings (2014). 64: 302. Archived(PDF) from the original on March 8, 2021. Retrieved July 11, 2021– via United States Department of Agriculture: United States Forest Service. Many sources of milkweed seeds require stratification (cold, moist treatment) before sowing. In a review of stratification requirements for common milkweed, recommendations varied from as short as 7 days to as long as 11 months at 5°C (41°F) (Luna and Dumroese, 2013). Butterfly milkweed (A. tuberosa) germination increased from 29 to 48 to 62% as stratification duration increased from 0 to 30 to 60 days, respectively (Bir, 1986). Our informal natural stratification trial with showy (milkweed) and narrow leaf milkweed (A. fascicularis) in southern Oregon revealed that seeds began to germinate after 15 weeks in stratification (Fig. 3A).
Higgins, Adrian (May 27, 2015). "7 milkweed varieties and where to find them". Home & Garden. The Washington Post. Archived from the original on September 26, 2020. Retrieved October 17, 2020. Seed may be stubborn to germinate and may need a period of cold treatment.
Gomez, Tony. "Asclepias syriaca: Common Milkweed for Monarch Caterpillars". Monarch Butterfly Garden. MonarchButterflyGarden.net. Archived from the original on March 16, 2015. Retrieved October 17, 2010. Start seeds indoors 2 months before final frost- seeds must be cold stratified.
"Asclepias syriaca". Butterfly gardening & all things milkweed. Archived from the original on July 7, 2015. Retrieved July 7, 2015. germination: seed requires cold moist period.
Landis, Thomas D.; Dumroese, R. Kasten (2015). "Propagating Native Milkweeds for Restoring Monarch Butterfly Habitat: Propagating Native Milkweeds: Seed Propagation"(PDF). International Plant Propagators' Society, Combined Proceedings (2014). 64: 302. Archived(PDF) from the original on March 8, 2021. Retrieved July 11, 2021– via United States Department of Agriculture: United States Forest Service. Any of the standard seed propagation methods (Landis et al., 1999) are effective with milkweed. Direct sowing of non-stratified seeds during the fall followed by exposure to ambient winter conditions can be effective, but the seeds must be mulched and protected. Cover sown seeds with a thin mulch; research has found that common milkweed seeds germinated better when planted 1 to 2 cm (0.4 to 0.8 in.) deep than when at the soil surface (Jeffery and Robison, 1971).
Butterfly Society of Virginia (2019). "Growing Milkweed". Archived from the original on June 24, 2019. Retrieved December 25, 2023. I've grown butterfly weed, swamp milkweed, Asclepias currassavica (bloodflower), Asclepias syriaca (common milkweed), and Asclepias verticillata (whorled milkweed). I've found that butterfly weed is the least favorite of my Monarch guests in my Virginia Beach garden for laying eggs (perhaps the leaves are tougher?)
Gunn, John (May 20, 2016). "Milkweeds (mostly Asclepias spp.)". Alonso Abugattas Shares Native Plant Picks for Wildlife. Mid-Atlantic Gardener (John Gunn). Archived from the original on October 21, 2020. Retrieved October 17, 2020. And if you have hot, dry conditions in your yard, try Butterflyweed (A. tuberosa). .... It's the least favored by Monarch caterpillars because it has very little toxin (cardiac glycosides) in its leaves.
Abugattas, Alonzo (January 3, 2017). "Monarch Way Stations". Capital Naturalist. Archived from the original on June 5, 2017. Retrieved June 5, 2017– via Blogger. (A. tuberosa) is the least favored by monarch caterpillars .... because it has very little toxin (cardiac glycosides) in its leaves, .... .
"Butterfly Weed: Asclepias tuberosa"(PDF). Becker County, Minnesota: Becker Soil and Water Conservation District. Archived(PDF) from the original on September 11, 2020. Retrieved September 11, 2020. Unlike other milkweeds, this plant has a clear sap, and the level of toxic cardiac glycosides is consistently low (although other toxic compounds may be present).
Abugattas, Alonzo (January 3, 2017). "Monarch Way Stations". Capital Naturalist. Archived from the original on March 8, 2021. Retrieved July 5, 2021– via Blogger. A better option for most gardeners might be Swamp Milkweed (A. incarnata) which, despite its name, does fine in regular garden soil and doesn't spread by runners.
"Asclepias incarnata". Bring Back The Monarchs. Monarch Watch. Archived from the original on June 12, 2021. Retrieved July 5, 2021. Life span: In gardens most plants live two-five years but known to survive up to 20 years. .... Propagation: Slow to spread via seeds. .... 'Overhead Conditions: Not shade tolerant. An early successional plant that tends to grow at the margins of wetlands and in seasonally flooded areas. It is not a good vegetative competitor and tends to disappear as vegetative density increases and habitats dry out.