On Gossamer Wings: The Lycaenidae Butterflies

  • Male and female Acmon Blue on deerweed. Photo: Marc Kummel
    Male and female Acmon Blue on deerweed. Photo: Marc Kummel
  • Male and female Gorgon Copper on golden yarrow. Photo: Marc Kummel
    Male and female Gorgon Copper on golden yarrow. Photo: Marc Kummel
  • A Gray Hairstreak showing the false “eyes” on the wings. Photo: Marc Kummel
    A Gray Hairstreak showing the false “eyes” on the wings. Photo: Marc Kummel
  • A Mormon Metalmark nectaring on buckwheat. Photo: Marc Kummel
    A Mormon Metalmark nectaring on buckwheat. Photo: Marc Kummel
  • A Silvery Blue on the flowerhead of black sage. Photo: Marc Kummel
    A Silvery Blue on the flowerhead of black sage. Photo: Marc Kummel
On Gossamer Wings: The Lycaenidae Butterflies

The Lycaenidae family of butterflies—blues, hairstreaks, coppers, and metalmarks, are usually small and very delicate looking, many of them brilliantly colored and some with very interesting life cycles. The apparent fragility of these tiny creatures earned the family the common name gossamer-winged but the vigor apparent in their life strategies belies this moniker.

This is the second largest family of butterflies, with almost 6,000 species worldwide, but named species are often termed “complexes” because there is still so much to be learned about their anatomy and behaviors. New species are still being discovered, and not just in the tropics. A new “blue” was discovered and named right here in California as recently as 1998!

My Ceanothus ‘Ray Hartman’ is in full glorious bloom in my hedgerow and this always seems like the start of butterfly season to me. So many lepidopteran species associate with the many different ceanothus species, and the Spring Azure, also called the Echo Blue (Celastrina ladon echo) is one of the first in early spring.

The Spring Azure uses several different host plants in succession, and in a good year may have three or even four broods. The first brood is often on ceanothus, and second broods on California buckeye, but they also use creek dogwood and cream bush as larval host plants. Larvae have also been recorded on huckleberries, chamise, and even blackberries!

Ceanothus, besides being a beautiful, drought-tolerant shrub (mine get no additional summer water once established) is a plant with numerous resources for wildlife. The flowers are buzzing with bees and all sorts of small insects, and many different birds and insects forage for seed once it has matured.

The number of butterflies that use ceanothus as a larval host plant is astounding: California Tortiseshell, Pale Swallowtail, Hedgerow Hairstreak and California Hairstreak, Pacuvius Duskywing, as well as the Spring Azure. Not to mention the other lepidopteran species whose larvae feed on the foliage. I once brought in what I thought were caterpillars of the Tortiseshell, but they proved to be the Common Sheep Moth! This is an incredibly beautiful day-flying moth, and not at all common anymore; more on that in another posting!

The blues, coppers, metalmarks and hairstreaks are uncommon in Marin gardens; many of them have associations with just one or two species of native plants in specific habitats. There is just one butterfly within the sub-family of hairstreaks that is often seen in Marin gardens and that’s the Common or Gray Hairstreak.

The Gray Hairstreak (Strymon melinus) is easy to spot, even among lots of other butterflies, because of a distinctive behavior: its wings are folded while it sips nectar, and it rubs its hind wings together steadily as it feeds. On both surfaces of the hind wing, close to the abdomen, are large black-pupiled red spots and delicate, highly mobile “tails.” The spots are vaguely like eyes, the tails like antennae, and the rubbing sets it all in motion, constituting a false head, which diverts predators away from the real body. It’s another wonderful example of back-to-front mimicry!

I like to spend a good bit of time in my garden just looking carefully to see what creatures are visiting the plants and flowers. The native buckwheats are now in full bloom in my garden, a little early this summer, and they attract a lot of insects. Native bees, hover flies and butterflies all find resources in the hundreds of tiny individual flowers arranged in compound umbels. The smaller umbels are like tight rounded pom-poms, and there are sometimes hundreds of these small pom-poms arranged together to make up the larger umbel. So many tiny flowers, each one with nectar and pollen, makes it a very energy-efficient resource for insects. Various buckwheat species produce flowers in shades of yellow, pale pink to deep reddish pink, or white; they all fade to a really attractive reddish-brown color as the seeds set, and the flower umbels persist on the plant right through to the rainy season.

The flowers of St. Catherine’s lace (Eriogonum giganteum), the largest of the native buckwheat species, are white and held in huge compound umbels that can be eight to ten inches or more in diameter! The plant itself can grow to be quite tall, a lot depends on exposure; I have one specimen that is over six feet, and now above the reach of the deer; another that stays at about four feet and is still caged to protect it from deer browsing.

Gray Hairstreaks frequently nectar on my buckwheats, and look very similar at a glance to the California Hairstreak (Satyrium californica); both are no more than an inch and a half, wingtip to wingtip, and both are a grayish-brown color, but the underwing pattern of the Gray is a series of fine white- and red-edged lines, while the pattern on the California Hairstreak is a series of delicate dots.

But the biggest difference, and the reason that the Gray is more common, is that it is highly polyphagus, second only to the Painted Lady in the scope of plants from various genera that it will use as host plants for its larvae. Plants listed in most books as host plants are from the mallow, pea and spurge families, but always with a note that there are probably many other plants used as well since there are multiple generations each year. The adults have even been recorded ovipositing on some non-native plants like bottlebrush! This little butterfly flies throughout the year, and is often seen in urban and suburban areas where it visits many different flowers in gardens while seeking nectar.

In sharp contrast, the California Hairstreak is strictly a butterfly of riparian bottomlands and is now a rare sight in areas where populations used to occur. The only host plants are valley oaks (Quercus lobata) and mountain mahogany (Cerocarpus betuloides).

The larvae of the hairstreaks are slug-like creatures, like most of the Lycaenidae, and very different looking than most caterpillars, so when I found a creature like that feeding on a Sidalcea ‘Party Girl’ (mallow family) I didn’t know what is was and brought it in to observe closely. It was apparently in a late instar and quickly formed a pupa distinctly different than most other butterfly pupae. It proved to be a Gray Hairstreak!

But when I noticed a similar looking larva feeding on a buckwheat flower, I assumed it was one of the blues (which often use buckwheats as host plants) and brought it in to observe and raise. And I learned something new again: Gray Hairstreaks will sometimes use eriogonum as a host plant!