Johnson’s Hairstreak: Old-growth obligate
Written by:
Linda Kappen
Johnson’s Hairstreak, Callophrys johnsoni, is a butterfly of the Lycaenidae family. Johnson’s Hairstreaks are 1.5 inches. On the dorsal hindwing (DHW), both sexes are brown with two short tails that are white-tipped. The ventral hindwing (VHW) colors range from cocoa to chocolate brown and burnished chestnut with a few brown spots on the lower submarginal VHW. A thin white median line runs through the upper and lower VHW, with the lower hindwing line being more flattened in comparison to the zig-zagged line on the Thicket Hairstreak. The edges of the wings have a creamy to whitish fringe.
The host plant for the Johnson’s Hairstreak is Western Dwarf Mistletoe, Arceuthobium tsugense. This mistletoe grows on old-growth Western Hemlocks, Ponderosa Pine, and some species of fir trees. Eggs are laid singly on the mistletoe, and the larvae overwinter. The Johnson’s Hairstreak is single-brooded in the PNW.
The Johnson’s Hairstreak habitats are cool, moist old-growth conifer forests that have older forest trees surrounding old-growth stands. The habitat is similar to that of the Spotted Owl and other old-growth species of concern. Johnson’s Hairstreak is dependent on old-growth forests in our Siskiyou and Klamath mountains, the coast range, and disjunct populations of the Blue Mountains of northeast Oregon and western Idaho. These types of habitats are critical to the survival of the Johnson’s Hairstreak. Careful forest management of large areas around these habitats needs to be taken into serious consideration in preservation. This includes all understory plants, flowers, or bushes.
The Johnson’s Hairstreak will spend much of its time in the forest canopy. Flying down from the canopy, they receive nutrients from spring-fed mud and nectar from understory plants. Some nectar plants are dogbane, pussytoes, wild strawberry, Oregon Grape, Ceanothus velutinus (commonly known as Snowbrush Ceanothus), other ceanothus species, manzanitas, vine maple, and others.
Johnson’s Hairstreak can be seen in flight from June through July. The Johnson’s Hairstreak is classified as a species of concern in the state of Oregon, endangered in British Columbia, and with the state of Washington being a candidate for endangerment. Major threats to the Johnson’s Hairstreak are logging, pesticide use, mistletoe management, windstorms, and wildfire. Hybridization and competition for habitat with the Thicket Hairstreak, which also uses the mistletoe, are of great concern as well. Limited logging for many acres around older forest stands and old-growth stands would provide larger habitat areas for both species.
I have seen Johnson’s Hairstreak only at Oregon Caves National Monument and Preserve on our yearly butterfly survey with the OCNM. Some researcher friends I know have seen them at Cascade Siskiyou National Monument and surrounding forested areas, Klamath County forests, forests surrounding the Oregon Caves National Monument, Lassen Volcanic National Park, Lassen National Forest, and Rogue River Siskiyou National Forest.
One fun fact is that the Thicket Hairstreak Callophrys spinetorum uses mistletoes in mature forests, as the Johnson’s Hairstreak does. However, the Thicket Hairstreak can be two-brooded. Larvae of both species overwinter.
Much of the preferred habitat has been logged in many places. It will be a challenge here as more public lands are threatened with clear-cut logging, on older successional forests, and old-growth logging. Hopefully, we will be able, as a public, to demand that our forests' health be taken seriously.
Linda Kappen
Photo 1: Johnson's Hairstreak at Oregon Caves National Monument. Photo: Linda Kappen
