Hemileuca eglanterina male, British Columbia,
courtesy of Leroy Simon.
TAXONOMY:Superfamily: Bombycoidea, Latreille, 1802 |
"Someone to Watch Over Me" |
The form denudata (northwestern Wyoming west to Washington, south through the Central Valley of California) has no markings on either wing.
The subspecies shastaensis, Grote, 1880, (northern California and southern Oregon) has a pink forewing with diffuse black markings or is mostly black with some pink spots.
The subspecies annulata, Ferguson, 1971, (Wyoming, Colorado, Utah) is narrowed to include specimens with suffuse black wing margins.
Moths fly from sea level to 8400 feet in a variety of habitats including chaparral, pine and redwood forests, oak woodlands, and riparian areas from Southeastern Alberta west to Vancouver Island, British Columbia; south to central Montana, Wyoming, central Colorado, northern Arizona, and southern California.
Here is a beautiful image sent to me by Steve Ife from British Columbia.
Preferred hosts vary with geographic conditons: Mountain lilac (Ceanothus), mountain-mahogany (Cercocarpus montanus), bitter cherry (Prunus emarginata), bitterbrush (Purshia tridentata), snowberry (Symphoricarpos), currant (Ribes), wild rose (Rosa), willow (Salix) and others.
They have been reported on Madrone Trees (Arbutus menziesii) in Sonoma County, California, May 12, 2009.
Females make their ovipositing flights from noon until 6:00 pm with all activity halting from midday until 1:30 when temperatures soar.
Hemileuca eglanterina male, California.
Hemileuca eglanterina female, British Columbia,
courtesy of Leroy Simon.
Hemieluca eglanterina third instars, anonymous
Larvae hatch the following year from mid May to June (earlier at high elevations) and are highly gregarious and black in the first instar. Larvae wander and become solitary feeders in the final stages.Larvae pass through five instars and urticating spines. Scan by Bill Oehlke. |
 |
Pupation is on the surface in a loosely fashioned cocoon under loose debris. Pupae often do not emerge until the following fall, giving this group a two year life history in northern and high altitude ranges.
Tuskes, Tuttle and Collins in The Wild Silkmoths of North America report that larvae can be quite variable and that larvae closer to the coast tend to be darker with less white maculation on the sides.
Richard Wasson provides theses observations: "This year has been unusually cool and wet and seems to have effected the
Hemileuca larvae development in my area of northern California. While out collecting larva last week (late May, 2010)
I found many that seem to be darker and not have as many hairs as normal. They also seem to be smaller that last year's
crop. I have attached a couple of pictures to show the difference between the normal and darker larva.
Does anyone know if this is common in a cooler year?
"I collected about 35 larvae in a two hour time frame.
I usually only find one or two larvae feeding on the same bush. I had assumed that the female laid a batch or two of
ova containing 20 to 50 ova at once. The same thing you see if keeping her in a bag over night. If this were the
case, you would expect to see 10 to 15 larva feeding on a single bush. The fact that I only find one or two per
bush suggest that she must move from bush to bush laying her ova. Another interesting observation is that
I find more larvae on bushes near the 10-acre lake than on bushes farther away for it. I am guessing that
flying over the lake looking for a spot to deposit their ova puts pressure on them to hit the next bush when
they reach shore."
Hemileuca eglanterina fifth instar, 15 miles north of Santa Rosa, Sonoma County, California,
May 26, 2010, darker, less hairy, feeding on Manzanita, and a few on Madrone, courtesy of Richard Wasson.
Hemileuca eglanterina fifth instar, 15 miles north of Santa Rosa, Sonoma County, California,
2009, more lateral white, hairier, feeding on Manzanita, and a few on Madrone, courtesy of Richard Wasson.
I wrote back to Richard: "They are supposed to be gregarious in early instars, becoming solitary feeders in late instars. Perhaps many have been picked off by birds or other predators. Maybe some have just wandered to other hosts."
Hemileuca eglanterina fifth instar, Shelton, Mason County, Washington,
August 27, 2011, courtesy of Glee Joy.
Hemileuca eglanterina fifth instar on pin cherry,
scan by Bill Oehlke
Amelanchier alnifolia |
Spreading dogbane |
Return to Hemileuca Genus
J. Steven McElfresh and Jocelyn G. Millar
Populations along the eastern edge of the Sierra Nevada Mountains contain both pheromone types, and an intermediate type. Antennae from the different pheromone types gave different EAG responses when challenged with blends of the pheromone components, with San Gabriel Mountains males showing a large response to E10,Z12-16:Ac and lesser responses to E10,Z12-16:OH and E10,Z12-16:Ald.
In contrast, antennae from Nevada males exhibited a large response to E10,Z12-16:OH, a smaller response to E10,Z12-16:Ald, and minimal or no response to E10,Z12-16:Ac. Males from the eastern Sierra Nevada Mountains gave antennal responses similar to those of either San Gabriel Mountains or Nevada males. However, eastern Sierra populations also contain an intermediate type which does not occur in areas where the major pheromone types do not occur together.
This third type may be a hybrid between the two other pheromone types, and it is attracted in approximately equal numbers to synthetic pheromone lures with and without E10,Z12-16:Ac. The existence of the different pheromone types, some of which are sympatric with closely related species, may represent a case of reproductive character displacement.
OR 27
Department of Entomology, University of California, Riverside CA,
92521, USA
Return to Hemileuca Genus