Callophrys [Mitoura] nelsoni
Nelson’s Hairstreak

Family Description:
Alternate Common Names:
Cedar Hairstreak, Olive Hairstreak.
Note: Some authors consider this species to be a complex of several species or subspecies.

Caterpillar: The caterpillars generally are green, marked with yellow or white, and appear bumpy. The average, full-grown length is 5/8 inch.
Adult: The butterfly is small, with a wingspan of 7/8 to 1 1/16 inches, and has a thin "tail" extending from the hindwing. Typically, the male is dark grayish to orangish brown on the upperside and marked with rust brown spots. The female is rust to brown on the upperside, with darker brown near the body and along the wings’ edges. Underneath, both sexes are typically light brown to orangish brown, possibly tinged with pink or purple. Many individuals are marked on the underside of one or both wings with an irregular, thin white line. Additionally, the underside of the hindwing may be spotted with orange, blue, or black near the tail.

This species ranges from southern British Columbia south through most of Washington and part of northern Idaho, through the Cascades of Oregon and into California.

It occurs in coniferous forests.


Caterpillar: Caterpillars feed on incense cedar (Calocedrus decurrens) and western red cedar (Thuja plicata).
Adult: Butterflies drink flower nectar.

There is only one generation of caterpillars each summer. Each undergoes five to seven stages of growth, called instars. The caterpillar is equipped with a honey gland, also known as a dorsal nectary organ, which emits a sugary solution agreeable to ants. The ants feed on the solution and in turn protect the caterpillar from predators. The caterpillars are colored in such a way that they mimic the foliage tips of their host plant. Pupae overwinter in a physiological state called diapause. Adults generally fly from May through July. The thin "tail" on each of the hindwings of adults is thought to mimic insect antennae and thus misleads bird predators into biting at the wrong end and only getting a mouthful of wing, while the butterfly escapes in the other direction.

Although not officially reported, males are thought to perch to wait for receptive females. Eggs are laid singly on the tips of host plant foliage.

Idaho Status: Unprotected nongame species.
Global Rank: G5; Population levels are secure, but may be of concern in the future.

Ballmer, G. R. and G. F. Pratt. 1988. A survey of the last instar larvae of the Lycaenidae of California. Journal of Research on the Lepidoptera 27:1-81.

Ferris, C. D. and F. M. Brown. (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies.   Second Edition.  Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.