Saturday, March 21, 2020

Species profile: Hemileuca of the northwest

There are four species of Hemileuca (buckmoths or sheepmoths) in the Pacific Northwest: Nevada Buckmoth (H. nevadensis), Elegant Sheepmoth (H. eglanterina), Nuttall's Sheepmoth (H. nuttalli) and Hera Buckmoth (H. hera).

I posted a short profile here on Hemileuca eglanterina in 2011. Over the next few days, I plan to post profiles of H. hera  and H. nevadensis. Hemileuca nuttalli is the only one of these four species I have yet to rear or even see, hopefully I will be able to post photos of it in the coming years!

Range & Flight Period
The Nevada Buckmoth is least common, occurring in willow habitats along the Snake River at the Oregon-Idaho border, the Columbia River at the eastern Washington-Oregon border, and as far north as George, Washington. It likely occurs elsewhere in eastern Oregon and southern Idaho, but often goes unnoticed due to the adults flying in late September and October. Nuttall's Sheepmoth occurs in sage-steppe habitat throughout eastern Washington, eastern Oregon and southern Idaho. It flies from late July to September. Hera Buckmoth occurs throughout the same area as Nuttall's and fly during the same period, but Hera appear to be more common. Elegant Sheepmoths are the most common and widespread of these four species in our area and the only one to occur west of the Cascades. They can be found in most woodland, prairie and upland habitats in Washington, Oregon and Idaho and fly from late May to September, peaking in July. All four species are day-flying and are often mistaken for butterflies by the casual observer.

Overwintering stage:
Nevada Buckmoth overwinters as eggs and therefore has a one-year life cycle.
Elegant Sheepmoth overwinters as eggs (one-year life cycle) in most areas. Higher elevation and northern populations overwinter as both eggs and pupae and have a two-year life cycle.
Hera Buckmoth and Nuttall's Sheepmoth usually overwinter as both eggs and pupae for a two-year life cycle, but some may have a one-year cycle in warmer seasons or low elevations.

Larval host:
Nevada Buckmoth feeds on willows and cottonwoods.
Hera Buckmoth feeds on sagebrush (Artemisia spp.).
Nuttall's Sheepmoth feeds on bitterbrush (Purshia tridentata) and snowberry (Symphoricarpos spp.).
Elegant Sheepmoth feeds on a variety of hardwood trees and shrubs including wild rose (Rosa spp.), hawthorn (Crataegus spp.), serviceberry (Amelanchier alnifolia), snowberry (Symphoricarpos spp.), cherries (Prunus spp.), snowbrush/buckbrush (Ceanothus spp.), willows (Salix spp.), and bitterbrush (Purshia tridentata).

Adults of Hemileuca, like other members of the Saturniidae family, do not have developed mouthparts and therefore do not feed.

Nevada Buckmoth 50-70 mm
Elegant Sheepmoth 65-87 mm
Hera Buckmoth 71-93 mm
Nuttall's Sheepmoth 69-83 mm

Nevada Buckmoth - Hemileuca nevadensis (male)

Elegant Sheepmoth - Hemileuca eglanterina (male)
Hera Sheepmoth - Hemileuca hera (female)

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