Moths are mysterious little pollinators, flitting around in the dark or near-dark, hard to observe. Yet providing plants that support them, so that they can pollinate, is important. Like other insects, their numbers seem to be dropping. Here are some ideas for gardens that promote moths.
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| white lined hawk moth (Hyles lineata) and Persian cat mint (Nepeta racemosa) |
Pollinating moths need food as adults, so they visit plants which provide nectar. Since they fly in twilight or dark, the plants have open their flowers then. In the United States, native plants that are moth-pollinated include tobaccos (Nicotiana), evening primroses (Oenothera and plants formerly called Gaura, now Oenothera species), four o'clocks (genus Mirabilis, including many small native species), jimson weeds (Datura species) and white morning glories (Ipomoea) as well as sand-verbenas (genus Abronia). Some honeysuckles are moth-pollinated for example the native coral honeysuckle (Lonicera sempervirens) and Eurasian species (Italian woodbine, Lonicera caprifolium, and Japanese honeysuckle L. japonica) as are some species of phlox (Phlox).
Classically, moth-pollinated plants are described as being white- or pale-flowered plants with lovely scents, the flower held out beyond the leaves and with a deep tube full of nectar. Many such plants are definitely moth-pollinated and some are pollinated only by moths. The moth-pollinated plants in the previous paragraph feature these evening- or night-blooming white flowers. Really nice to have in the garden!
Looking at the pictures online, however, there are a lot of photos of hawkmoths visiting brightly colored flowers. In my yard I look for them on the purple flowers of catmint (Nepeta racemosa). Everyone speaks of them pollinating four o'clocks (Mirabilis), for example the desert four o'clock Mirabilis multiflora, but it has magenta flowers. Four o'clocks have strong markings in the ultraviolet which many lepidoptera can see (link link), possibly other moth-adapted flowers that seem dark to us do too.
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| desert four o'clock Mirabilis multiflora moth pollinated but not the classical color (flowers about 1/2 the size of a petunia) |
Online, there are numerous photos of moths taking nectar from plants neither pale nor with obvious long tubes for nectar (example: note in particular the blazing star, Liatris). In online photos, you can also see sphinx moths feeding at multicolored petunias (Petunia), swamp milkweed (Asclepias incarnata), bee balm (Monarda fistulosa), blue phlox (Phlox species), dandelions (Taraxacum officinale), sages (Salvia species), columbines (Aquilegia) coral honeysuckle (Lonicera sempervirens), plumbago (Plumbago zeylanica), thistles (Cirsium and Carduus species), lilacs (Syringia), penstemons (Penstemon), coralberry (Symphoricarpos) carnations/pinks (Dianthus species), vervains (Verbena), red valerian (Centranthus ruber), zinnias (Zinnia species), Rocky Mountain bee plant (Cleome serrulata), and a currant (Ribes ). Reds and yellows, purples and oranges, narrow, shallow tubes, flat flowers, all kinds of flowers. (Search "hawk moth" and see for yourself. Some pictures may be staged or the flower was in the background as the moth went by, but you can see the proboscis probing many flowers that are not white or tubular.) This suggests many species of flowers will feed moths.
A yard with many flowers, from spring to fall, that includes some of the above plants, will be a welcoming place to moths. Being careful to include some flowers that are open at dusk and into the night will make it even better.
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| Bee balm, Monarda fistulosa |
Growing host plants for moth larvae is trickier. Beautiful sphinx moths' caterpillars are called tomato and tobacco horn worms and feed on tomatoes (Solanum lygopersicum), eggplants (Solanum melongena) and chilis (Capsicum species), as well as wild species in the tomato family (Solanaceae). They get to be big caterpillars and will strip a tomato plant of its leaves, so if you want to grow tomatoes and chilis to aid these dramatic insects, plant enough to share with the sphinx moths.
There are more than 80 species of sphinx moths (hawk moths, hummingbird moths, in the insect family Sphingidae) native to North America. The list of host plants on which they have been found feeding is very long. They may have preferences, but many sphinx moth larvae can feed on a variety of plants, often unrelated plants. Willows (Salix), ash (Fraxinus), trumpet creeper (Campsis radicans), evening primrose species (Oenothera species), wild grape (Vitis), Virginia creeper (Parthanocissus) and wild plum (Prunus) have all be observed as hosts. Most areas in the United States have about five species of native sphinx moths, more as you go south to Florida and Arizona. What I'm going to do this year is to check that I have host plants used by one or two of my local sphinx moths and add plants for additional moth species in the future.
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| old photo of big sphinx moth larva feeding on an evening primrose (Oenothera) |
Settling moths, moths of families other than the Sphingidae, are less well-known. Some groups have been well-investigated. The moths that pollinate campions (Silene, carnation family Caryophyllaceae), Hadena species in North America, mostly feed on one or more species of campion as well, so a good stand of campions (also called catch-fly and Indian pinks) should help both adult and juvenile moths. Yuccas (Yucca) and senita cacti (Senita) both feed on and are pollinated by their specialist moths, so plant to the plant you want pollinated to provide the host plant for its caterpillar.
It is a reasonable guess that every native American plant has at least one native moth species that consumes it. That leads me to the general advice for gardening for insects, which is to provide lots of different plants, plants from diverse plant families. It is the same approach as for butterflies, but with less information. Encourage the plants to form pretty big clumps. And leave standing dead all winter, cleaning up only once spring is well underway, unless you know that the moths do not overwinter somewhere in the old leaves.
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| plume moth, similar to Emmelina sp. (Pterophoridae) on small sunflower Helianthus pumilus in Colorado |
Making the yard friendly to moths looks like a great deal of fun, since they visit some of my favorite flowers.
References
see previous blogs on moths Moth Pollination 1. Overview. Moth Pollination 2. Sphinx moths Moth Pollination 3. Settling Moths
Kathy Keeler
A Wandering Botanist
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