DISTRIBUTION:

Hemileuca nevadensis (forewing length: males: 50-66mm; females: 55-70mm) flies from British Columbia, northern Saskatchewan and eastern Manitoba southward throughout most of the western and midwestern U.S. down into southern New Mexico and into Mexico: Baja California Norte.

It is regarded as extinct in former regions of California, presumably due to destruction of river woodlands.

Visit Hemileuca nevadensis male and fifth instar, Santee, San Diego County, California, courtesy of Ilayne Correa.

Hemileuca nevadensis courtesy of Robert Thompson copyright.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

This species flies from late September to early December. Willows and cottonwoods are the primary larval hosts.

ECLOSION, SCENTING AND MATING:

Eclosions take place in the early morning, just after sunrise, and females call a few hours later. Pairing is very brief, usually from 30 minutes to two hours and females make their ovipositing flights in the late afternoon and usually deposit from 100-200 beige ova in one or two egg rings on supporting twigs.

Hemileuca nevadensis ovipositing on willow, courtesy of Russell Witkop.

Hemileuca nevadensis courtesy of Robert Thompson copyright.

EGGS, LARVAE, COCOONS AND PUPAE:

Hemileuca nevadensis hatchlings, courtesy of Bonnie Caruthers.

Larvae hatch in late March through May 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 at least five larval instars (usually six) and larvae like hot, dry conditions. They would not do well in a jar, and they are better reared outdoors in sleeves, probably on willow, exclusively. Pupation is on the surface in a chamber fashioned under loose debris. Pupae eclose that fall in October and November just prior to the rainy season.

Hemileuca nevadensis courtesy of Dave Wikle, image rotated.

Hemileuca nevadensis, fifth instars, June 4, 2008,
Prado Basin, Riverside County, California, courtesy of Bedros Orchanian.

It is difficult to distinguish between Hemileuca nevadensis and Hemileuca maia. Tuskes, Tuttle and Collins indicate possible presence of one or more cryptic species in the mix. The following images from Thomas Jantscher from Monona County, western Iowa, could be H. nevadensis or something as yet undescribed. Note the black dorsal spinage as opposed to more yellow spinage of nevadensis from more western populations.

Hemileuca nevadensis fifth instar, Monona County, Iowa,
July 5, 2013, courtesy of Thomas Jantscher.

Hemileuca nevadensis female, Monona County, Iowa,
October 13, 2013, courtesy of Thomas Jantscher.

Larval Food Plants

Willow species would be the preferred food plant.

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.

Acer rubrum Corylus Populus fremonti Populus tremuloides..... Prunus Quercus agrifolia Salix babylonica Salix discolor Salix interior Salix lasiandra Salix lasiolepis Salix longifolia

Red maple Hazel Fremont cottonwood Quaking aspen Cherry/plum Coast live oak Weeping willow Pussy willow Sandbar willow Willow Arryo willow Sandbar willow

CAL PHOTOS courtesy of Gerald and Buff Corsi

Hemileuca nevadensis fifth instar, found on willow, Mission Trails Regional Park,
San Diego County, California, June 18, 2011, courtesy of Christine Rogers.

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