South Palm Wash 1
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Anza-Borrego Desert Animals & Plants
South Palm Wash, Anza-Borrego Desert State Park
© W.P. Armstrong 16 April 2009

The Seldom-Seen Moth Lacewing (Oliarces clara)

The North American genus Oliarces contains only one species, O. clara. It was discovered in1908 near Mecca, California approximately 13 kilometers northwest of the Salton Sea. The original type locality, called Walter's Station, was an early watering stop for steam locomotives along the Southern Pacific Railroad. It was not collected again until 1949 near Earp, California (Parker Dam area). Since then, a few collections have been made near Yuma, Arizona; Telegraph Pass in Yuma County, Arizona; near Palm Springs and Deep Canyon in Riverside County; near Glamis in Imperial County, California; road between Rice and Blythe, California; and Boulder City, Nevada. A recent discovery by James Dillane in South Palm Wash on 10 April 2009 is the first documented location for San Diego County. I revisited the slot canyon above the wash on 16 April 2009 and found one individual clinging to the vertical canyon wall. It is not known whether the adult emerged from the ground in this canyon, or whether it was carried to this sheltered location by strong winds. Special thanks to Alison Oblites for finding the latter individual on the canyon wall.

Deep slot canyon that drains into South Palm Wash.

A moth lacewing (Oliarces clara) clinging to vertical canyon wall.

Seven species in the family Ithonidae have been described, and all of them occur in Australia except for Oliarces clara, a native of the American southwest desert region. Larvae in the wild have only been found associated with the roots of creosote bush (Larrea tridentata). Feeding on roots is unusual for Neuropterans, because most species are predaceous. It is curious why this insect is seldom seen, and yet its host shrub is the ubiquitous creosote bush (Larrea tridentata) that dominates the vast desert region of Mexico and the southwestern United States. More research is needed on this fascinating insect.

Larrea tridentata is a relatively recent colonizer of North America. It first appeared in fossil packrat middens during the late Quaternary, approximately 18,700 years ago. This species likely arrived in North America as a result of long-distance dispersal from South America, and was probably derived from an ancestral population of L. divaricata which is widespread in Argentina, Chile and Peru. Since the last period of glaciation in the United States (12,000 years ago), as warm deserts formed in Mexico and the American Southwest, L. tridentata expanded its range to include the present-day Chihuahuan, Sonoran and Mojave Deserts. During this range expansion, it evolved into different polyploid races: In the Chihuahuan Desert the plants have the normal diploid number (2n=26) like the plants in Argentina. Sonoran Desert plants are tetraploid (4n=52) and those in the Mojave Desert are hexaploid (6n= 78). The extra genetic material in the polyploids may provide more adaptibility, such as survival in colder climates of the Mojave Desert. The oldest creosote bush clone in the Mojave Desert studied by Dr. Frank Vasek at UC Riverside was dated at 11,700 years old. If these colonization dates are accurate, It must have been one of the early creosote bush seedlings in this region.

  • Duran, K.L., Lowrey, T.K., Parmenter, R.R., and P.O. Lewis. 2005. "Genetic Diversity in Chihuahuan Desert Populations of Creosotebush (Zygophyllaceae: Larrea tridentata)." American Journal of Botany 92: 722-729.

It would be interesting to know when the moth lacewing colonized these creosote bush scrub habitats in North American, and whether it also coexists with South American populations of Larrea divaricata. The fossil of a rapismatid-like species of Ithonidae (Principiala incerta) was recently discovered in the lower Cretaceous Crato Formation of northeastern Brazil.

  • Makarkin, V.N., and F. Menon. 2007. "First Record of Fossil 'Rapismatid-Like' Ithonidae (Insecta, Neuroptera) From the Lower Cretaceous Crato Formation of Brazil". Cretaceous Research 28: 743-753.

According to Faulkner (1990), the adults emerge from the soil and mate during a four-day period during mid-April to mid-May. Adults have a wingspan of 35 to 40 mm (1.6 inches). Moth lacewings are reportedly weak flyers and are easy prey for birds and other predator insects. They apparently do not feed as adults and soon die after the mating period. Adult females in captivity lay their eggs on the soil. After the eggs hatch, the grub-like larvae are believed to burrow into the soil and attach to plant roots. For more information, please refer to the following reference by David Faulkner:

  • Faulkner, D.K. 1990. "Current Knowledge of the Biology of the Moth-Lacewing Oliarces clara Banks (Insecta: Neuroptera: Ithonidae)." Advances in Neuropterology. Proceedings of the Third International Symposium on Neuropterology, Pretoria, R.S.A. pp. 197-203.

During their short adult life, moth lacewings apparently find their mates by a phenomenon known as "hilltopping." They simply fly upslope to the summit of the nearest hill or ridge. This method of mating is also used by members of the order Lepidoptera. During the summer months in San Diego County, it is common to find dozens of species of butterflies chasing each other in rather erratic flying behavior at the tops of chaparral-covered hills. These remote mountain tops are popular meeting places for sexually active insects looking for mates.

Moth lacewing (Oliarces clara), a seldom-seen desert species in the family Ithonidae.

Hydrophyllaceae: Phacelia crenulata var. ambigua (Desert Phacelia)

Desert blister beetle (Lytta magister) on Phacelia crenulata.

Stink Bugs (Pentatomidae) On Blazing Star and Arizona Lupine

Stink bug nymph on a blazing star (Mentzelia involucrata).

Stink bug adult on Arizona lupine (Lupinus arizonicus).

Asteraceae: Xylorhiza orcuttii (Orcutt's Woody Aster)

Polemoniaceae: Langloisia setosissima ssp. setosissima (Bristly Langloisia)

Polemoniaceae: Aliciella latifolia ssp. latifolia (Broadleaf Gilia)

Onagraceae: Camissonia cardiophylla ssp. cardiophylla (Heart-Leaved Evening Primrose)

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