Watch Out for this Plant

In a talk to our group two years ago, Jon Pelham discussed butterfly foodplant guilds. He defined a foodplant guild as a plant species that supports at least three species of butterflies as a distinct community in an ecosystem. This plant is durable and persistent over time and over a considerable area. He suggested that several buckwheats were guild plants. Eriogonum elatum, Tall Buckwheat, is one of Cascadia’s guild foodplants that supports at least seven butterfly species according to Dave Nunnallee in “Buckwheats of Washington”. Since the writing of his booklet, one additional species has been added bringing the total to eight butterfly species: Blue Copper, Western Green Hairstreak, Sheridan’s Green Hairstreak, Gray Hairstreak, Columbia Dotted Blue, Acmon Blue, Lupine Blue, Mormon Metalmark. In addition to being a host plant, it is an excellent nectar source for butterflies throughout the season, and is a plant to seek out when you are in the field!

Tall Buckwheat is one of our native buckwheats and is found east of the Cascade Crest from the shrub-steppe to higher elevations such as Red Top Lookout. This plant may found growing along roads, hillsides or in meadows, and some- times in abundance. As the name implies, it is a tall plant growing up to 4 feet. This luxuriant species was one of the first of our many buckwheats that I was able to recognize. It has a tall hollow green stem that rises from large, basal leaves. The stem branches at the top where small pink and white flowers bloom from June to September. The top branching is fairly open and gives the plant a lacy appearance during its long blooming season.

The eight known butterfly species that use Tall Buckwheat as a food plant may be found during different times of the season. For example, Sheridan’s Green Hairstreak has an early flight time while the Mormon Metalmark flies late in the season. Depending on the flight time of the species, various parts of the plant may be used: the tender, unfurling leaves of early spring, the mature leaves as the season progresses, or the flowers. Some species use both the leaves and flowers, and one late season species sometimes uses the stem.

Three of these species that use Tall buckwheat as a food plant are Hairstreaks. The early Sheridan’s Green Hairstreak, Callophrys sheridanii, is one of Cascadia’s early fliers. The range for this species is from the shrub-steppe to subalpine mountains in the eastern part of our state. The eggs are laid on the young leaves of Tall Buckwheat. At higher elevations, the larva feeds on flowers. This species also uses other Eriogonum as host. The mature larva then looks for protected areas, such as leaf litter, for pupation and winter diapause. The Western Green Hairstreak, Callophrys affinis, flies a bit later, but they may overlap in some areas. This species ranges along an area on the east side of the Cascades and also in the Blue Mountains. It is thought that the species lays eggs on young leaves early in the season and flowers later. This species also uses other Eriogonum as host. The Western Green Hairstreak, like the Sheridan’s Green Hairstreak, overwinters as a pupa in plant litter on the ground. The third Hairstreak, one of our most common butterflies, is the Gray Hairstreak, Strymon melinus, and is seen in most parts of our state. The larva feeds on leaves or flowers and the pupa overwinters. This species flies from April to October and may have three broods. A wide variety of host plants are used by this species including Tall Buckwheat.

Hedgerow Hairstreak

Three of our Blues use Tall Buckwheat as host plant. The Columbia Dotted Blue, Euphilotes columbiae, is one of the more common Euphilotes that you will see in the Columbia Basin. This species makes use of two buckwheats, one being the Tall Buckwheat. Eriogonum compositum is used as well. Eggs are laid on the flowers. The larva eats flowers and fruit, sometimes being attended to by ants (myrmecophily). The pupa overwinters. Acmon Blue, Icaricia acmon, may be seen in habitats from the shrub-steppe to alpine meadows. There will be one brood at high elevations, two in hotter areas. Eggs are laid on flowers and leaves. This species uses other buckwheats as well as some lotus species. Pyle and LaBar state that the second instar overwinters. Lupine Blue, Icaricia lupini, has also been recovered from Tall Buckwheat.

The Blue Copper, Lycaena heteronea, uses many Eriogonum species as host including the Tall Buckwheat. However, it may be that Eriogonum compositum, Northern Buckwheat, is the preferred plant. We see this species from the subalpine meadows of the Cascades to the shrub-steppe of eastern Washington. Eggs overwinter. Ant attendance may occur when the larvae hatch the following season.

One of our late season fliers, the Mormon Metalmark, Apodemia mormo, uses several Eriogonums as host in our area including Tall Buckwheat. When I first saw this species on Tall Buckwheat while driving slowly along a country road, I stopped my car and quickly jumped out to take a photo. In my excitement, I left my car door open. The man in his truck behind me was not happy, but fortunately patient. This is a species of roadsides, canyons and the shrub-step of eastern Washington. James and Nunnallee show that after the overwintered eggs hatch in the spring, the larvae spend some time in a dormant state, then pupate late summer prior to their flying time. They can be seen late summer in the shrub-steppe nectaring on both Tall Buckwheat and Rabbitbrush.

Tall Buckwheat is a guild plant that is known to support eight species of butterflies. In addition, this author has observed the following species using this luscious plant as a nectar source: Dark Wood Nymph, Blue Copper, Snowberry Checkerspot, Hoary Comma, California Hairstreak, Hedgerow Hairstreak, Halfmoon Hairstreak, Gray Hairstreak, Behr’s Hairstreak, Boisduval Blue, Acmon Blue, Columbia Blue, Mormon Metalmark. This is a plant that gets me to stop my car and take a closer look at what might be flying. Get to know this plant and watch for it when you are in the field this summer! But make sure you close your car door when you stop!

Jon Pelham, WBA talk, “Butterfly Foodplant Guilds in WA State”, Dec. 6, 2017;

”Buckwheats of Washington”, David Nunnallee; Life Histories of Cascadia Butterflies, David James & David Nunnallee; Butterflies of the Pacific Northwest, Robert Pyle & Caitlin LaBar

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