Coloradia pandora Blake, 1863
Coloradia pandora, the Pandora Moth, is a very large (FW length 33–40 mm in males and 43–44 mm in females; wingspan 7.3–9.1 cm) heavy-bodied silkworm moth with loosely-scaled gray forewings and pink hindwings. The dark brown-gray forewings are variably suffused with light gray, greatest in the terminal area where the pale scales emphasize the jagged subterminal line. The other transverse lines are darker than the ground color, somewhat diffuse and zigzag in shape. The discal spot is round and black. The pale pink hindwings have gray veins toward the outer margin. The wings are marked with a black oval discal spot, a dark gray scalloped postmedian line, and a gray marginal band. The fringes of both wings are weakly checkered with white at the ends the veins. The body is dark gray and fuzzy, and long pink scales cover much of the gray abdomen. The antennae are yellow, widely quadripectinate in males and thinner and bipectinate in females.
Coloradia pandora is easily identified by very large size, hoary gray forewing, and pink hindwing with black markings. It is similar to several other Coloradia species, but none of them have ranges that approach the Pacific Northwest. This species cannot be confused with any other species in our area.
Pacific Northwest populations are referable to subspecies Coloradia pandora lindseyi Barnes and Benjamin. According to Ferguson (1971) it differs from other subspecies by its larger size, darker brown-gray forewings, and darker pink hindwings. Ferguson suspected that subspecies C. p. lindseyi is diurnal based on relatively small eyes and a report of day-time flight; however, this is not supported by our collecting experience.
The larva has very short black scoli or tubercles and is gray-black with white lateral and subdorsal dashes. It is illustrated by Miller and Hammond (2003).
This species is abundant in ponderosa pine forests at middle elevations along the east side of the Cascades in Oregon and frequently experiences epidemic outbreaks. During such outbreaks, it expands into the coniferous forests of western Oregon including the Siskiyou Mountains, Coast Range, and along the west slope of the Cascades.
Coloradia pandora is predominantly found in the mountains of western and southern Oregon in our region. It has been collected in Kittitas and Klickitat Counties in the Washington Cascades, and there are isolated records from southern Vancouver Island and south-central Idaho. The range of this species might be expanding northward.
Coloradia pandora is widely distributed in western North America. It is found throughout California east to southern Wyoming and western South Dakota in the north, and to west Texas in the south. It doubtless occurs in northern Mexico as well.
This species is a foodplant specialist feeding on species of pines (Pinus spp.) in the Pinaceae, which includes ponderosa pine (the main host plant), Jeffrey pine, lodgepole pine, pinyon pine, sugar pine and coulter pine. During epidemic outbreak years, it may also feed on Douglas fir in western Oregon. Development takes 2 years to complete. The first year larvae overwinter in clusters and the second year is spent as a pupae underground.
Adults have been collected from late June to early fall in the Pacific Northwest. They are nocturnal and come readily to lights. The females lay eggs in groups on pine trunks or needles. The moth has vestigial mouth parts and does not feed.
Caterpillars can occasionally become pests in pine forests, and are frequently an important defoliator of pines in western North America. Native Americans are reported to have gathered the mature larvae and roasted them for food.
Miller & Hammond (2003)
Peigler & Opler (1993)
Powell & Opler (2009)