Xanthorhoe labradorensis (Labrador Carpet Moth)

This is the ‘lifer’ moth I talked about in 5th Night of Moth Week . This is an elegantly patterned geometer, and was quite pleasing to my eye. The experts make a big deal about not being able to separate Xanthorhoe labradorensis from X. packardata without examining genitalia, and I would agree that superficially they are nearly identical. But really it didn’t seem as hard to find differences between these two moth’s appearance as it often is with other species, and seemed rather like much ado about nothing, especially since the life histories of the two species are assumed to be the same, at least in the absence of any concrete knowledge about X. packardata. Also, I’ve been told by someone I trust that X. packardata doesn’t occur in Washington or Oregon.

Considering the fact that the larvae of Labrador carpet moths are polyphagous generalists, I’m really surprised that I had never seen this moth before. And it is distinctive enough that I’d have noticed and remembered. But even with the wide range of larval hosts this may not be an abundant or even common moth, and location and timing are everything in the finding-new-bugs game.

Description– “Wingspan ≈ 25mm…A flimsy moth with a small body and broad wings. FW light grey, slightly mottled. Basal area is red brown, with prominent black AM. Median area, between AM and PM, is rust-red, with a small red-brown patch on the costa, before the apex. HW light grey.”

Similar species– Xanthorhoe packardata is very similar, and some folks say they can only be separated by genitalic dissection. However in looking at photos it appears that X. packardata has a more looping postmedial line, with a distinct, isolated, rounded projection near the costa that creates a grey tooth into the red band.

Habitat– Open woodlands and forest edges.

Range– Northern North America, though absent from the Great Plains; probably region wide in appropriate habitat in the PNW.

Eats– “…larvae are polyphagus with a range of mostly herbs but also some woody plants listed as hosts.” Xanthorhoe labradorensis – University of Alberta Museums Search Site

Eaten by– Presumably a host for parasitoids in Hymenoptera and Diptera, and probably preyed upon by insectivores of all classes, but I can find nothing specific for this species.

Adults active– Nocturnal; May into August

Life cycle– Univoltine; from the timing of adult flight I’d guess they over winter as late instar larva in diapause, but I can’t verify that.

Etymology of names– From the Greek words for ‘yellow stream’, referring to the wavy yellow lines on the forewings of some species in this genus. The specific epithet labradorensis refers to the location of the type specimen.