Hemileuca juno
Packard, 1872

Hemileuca juno from New Mexico. Photo by Joel Szymczyk

TAXONOMY: Superfamily: Bombycoidea, Latreille, 1802 Family: Saturniidae, Boisduval, [1837] 1834 Subfamily: Hemileucinae, Grote & Robinson, 1866 Tribe: Hemileucini, Grote & Robinson, 1866 Genus: Hemileuca, Walker, 1855

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DISTRIBUTION:

Single-brooded Juno (wingspan: males: 44-56mm; females: 57-66mm) which has forewing patterns and colouration, male genitalia, and larvae very similar to electra, flies in desert scrub from southern Texas, Arizona and New Mexico down to Sonora, Mexico. It has also been recorded in San Diego and Imperial counties, California, but those records are very old. It is doubtful that it flies in California.

Hemileuca juno male, Hueco Tanks State Park, El Paso Co. Texas,
54mm, Ocotber 29, 1994, courtesy/copyright Charles Bordelon and Ed Knudson.

Hemileuca juno female, Hueco Tanks State Park, El Paso Co. Texas,
57mm, Ocotber 29, 1994, courtesy/copyright Charles Bordelon and Ed Knudson.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

This species flies from late September to early December. Honey mesquite and screwbean mesquite are the primary larval hosts.

Hemileuca juno female from Arizona. Photo by Bruce Walsh.

Hemileuca juno male from Arizona. Photo by Bruce Walsh.

Hemileuca juno male, 18 W of Wilcox, Cochise Co., Arizona,
44mm, Ocotber 15, 2000, courtesy/copyright Charles Bordelon and Ed Knudson.

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 until dusk and usually deposit from 100-200 beige ova in one or two egg rings on supporting twigs.

Occasionally both males and females are taken at lights.

EGGS, LARVAE, COCOONS AND PUPAE:

Larvae hatch in April and May after overwintering in egg stage, and they are highly gregarious and gray/black in the first instar.

They begin feeding on buds and flowers of hostplants and tend to hide in the shade during the hot midday sun. Larvae wander and become solitary feeders in the third and fourth instars. There are five larval instars with larvae maturing at approximately 50 mm. Flowers and buds seem to remain preferred over foliage throughout development.

Larvae like hot, dry conditions and pupate in May or early June in loosely constructed cocoons under leaf litter. Image courtesy of J.B. Walsh.

Adults eclose that fall from September through November.

The following images of eggs, third and fith instar larvae and pupae are courtesy of Joel Szymczyk.

Non-member Bob Barber sends the following images from Otero County, New Mexico. He reports the May 29, 2009 date is the latest he has seen mature larvae in his area where they are common.

Hemileuca juno mature larva on mesquite, Dog Canyon, Otero County, New Mexico,
May 29, 2009, courtesy of Bob Barber.

Hemileuca juno mature larva on mesquite, Dog Canyon, Otero County, New Mexico,
May 29, 2009, courtesy of Bob Barber.

Larval Food Plants

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.

Gleditsia triacanthos..... Parkinsonia Populus deltoides Populus fremontii Prosopis glandulosa Prosopis juliflora Prosopis pubescens Salix

Honey locust Jerusalem thorn Eastern cottonwood Fremont cottonwood Honey mesquite Honey mesquite Screwbean mesquite Willow

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