Pacific Northwest Moths

Identification

Adults

Lasionycta illima is a small, day-flying species (FW length 12–13 mm) that flies in northern British Columbia in our region. It has a slightly bluish gray forewing and a cream-colored hindwing with a large, black discal spot and marginal line. The forewing is mottled blue-gray with warmer tan areas in the median area with gray lines and spots. The basal, antemedial, and postmedial lines are double, filled with the ground color, but usually indistinct. The inner component of the postmedial line is serrate. The subterminal line is pale and indistinct, but its position is evident due to dark gray suffusion medial to it. The fringe is checkered with gray and black. The orbicular spot is round and filled with light gray and a dark central ocellus. The reniform spot is filled with the ground color and is inconspicuous. The small claviform is black. The dorsal hindwing is slightly yellowish-white with a large, black discal spot, thin scalloped postmedial line, and a broad, well-defined marginal band. The fringe is two-toned, gray basally and white distally, and weakly checkered. The ventral hindwing is yellowish-white with a thick black postmedial line, a large discal spot, and a gray marginal band. The head and thorax are covered with black and white hair-like scales. The eye is moderately reduced in size. The male antenna is weakly bipectinate.

Lasionycta illima is the northern counterpart to Lasionycta poca—both have similar markings on the ventral hindwing. These species can be distinguished by locality. In its northerly range L. illima is closely similar to Lasionycta frigida and it is even possible that they are one and the same species. Lasionycta illima has a relatively thick postmedial line on the hindwing underside; that of L. frigida is thinner. Lasionycta illima could also mistaken for Lasionycta leucocycla or Lasionycta staudingeri in northern British Columbia. Lasionycta leucocycla has a yellow hindwing that lacks a postmedial line on the underside. Lasionycta staudingeri differs from L. illima in having olive patches on the forewing, an orbicular spot without a central dark "ocellus," and a more pure white hindwing with a pure white rather than two-toned fringe.

Habitat

This species is widely distributed but relatively rare in arctic-alpine tundra and taiga spruce habitats of northern British Columbia, Yukon, and Alaska.

Distribution

Pacific Northwest

Lasionycta illima is a rarely collected species with only a handful of records across its range. It has been collected at Pink Mountain. It also occurs within several miles of the British Columbia border near Carcross, Yukon Territory (Andre Langois, personal communication 2010).

Global

The range of this species extends to central Alaska through southern Yukon Territory.

Life History

Larvae

No information is presently available regarding larval foodplants of this species.

Adults

This species is single-brooded and flies in the summer during June and July. It is at least partially diurnal and has been collected during the day at Carcross, Yukon Territory by Andre Langois (personal communication, 2010).

Economic Importance

None.

Literature

Crabo & Lafontaine (2009)

Moth Photographers Group