DISTRIBUTION:

The Hemileuca nuttalli moth (wingspan: males: 63-70mm; females: 63-64mm), flies from south central British Columbia, throughout Idaho, in eastern Washington, Oregon and California, across Nevada and Utah into western Colorado, Wyoming and Montana.

Hemileuca nuttalli in flight, courtesy of Russell Witkop.

Hemileuca nuttalli uniformis is a darker form associated with higher elevations. Lemaire 2002 treats Hemileuca nuttalli uniformis (Cockerell, 1914) as a subspecies rather than a form. "There is less contrast between the forewing and hindwing and often diffuse black maculation."

Hemileuca nuttalli uniformis male, Almont, Colorado,
64mm, 13 August 1977, courtesy/copyright Charles Bordelon and Ed Knudson.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

This species flies from July to early September. Bitterbrush and Snowberry species are the primary larval hosts.

Hemileuca nuttalli male, copyright Kirby Wolfe

Hemileuca nuttalli male, Mono County, California, August 11, 2007, courtesy of Ruth Nielsen.

At first I had difficulty determining whether the Mono County moth was eglanterina or nuttalli, but the downward turn of the hindwing black pm line near the anal angle indicates nuttalli. In eglanterina, the same line is straight. Eglanterina also tend to have heavier and more extensive black markings on the forewing, often extending slightly into the median area.

There can be varying amounts of yellow-orange scaling on the forewings.

Hemileuca nuttalli female, W of Durango, La Plata County, Colorado,
65mm, 23 July 2002, 6000 feet, courtesy/copyright Charles Bordelon and Ed Knudson.

Charles Bordelon writes, "Though several of these were flying around when I was west of Durango 5 years ago, I only managed to catch one female. I was around 6000' feet on a ledge, so chasing these was not much of an option... They were around blue "scrub oaks," where Hypaurotis chrysaulis was perching. Nuttali just reaches this area, but I'd like to know more about this one."

ECLOSION, SCENTING AND MATING:

Eclosions take place in the morning and females call in the early afternoon. Pairing is very brief, usually from 30 minutes to two hours. Females make their ovipositing flights in the late afternoon and usually deposit from 15-50 eggs in numerous clusters on supporting twigs.

EGGS, LARVAE, COCOONS AND PUPAE:

Larvae hatch in May and early June after overwintering in egg stage, and they are highly gregarious and black in the first instar.

Larvae wander and become solitary feeders in the third and fourth instars. There are five larval instars.

Hemileuca nuttalli larva courtesy of Steve Ife.

Pupation is on the surface in a chamber fashioned under loose debris. Most pupae eclose that fall but some overwinter for at least one year, particularly at higher elevations.

Wing colouration and patterning varies considerably.

Hemileuca nuttalli male, courtesy of Steve Ife, British Columbia.

Larval Food Plants

Listed below are primary food plant(s) and alternate food plants listed in Stephen E. Stone's Foodplants of World Saturniidae. It is hoped that this alphabetical listing followed by the common name of the foodplant will prove useful. The list is not exhaustive. Experimenting with closely related foodplants is worthwhile.

Cercocarpus betuloides Purshia tridentata Pyracantha Symphoricarpos albus Symphoricarpos oreophilus.....

Birchleaf cercocarpus Antelope bitter brush Firethorn Snowberry Mountain snowberry

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