Harrisina metallica
Stretch, 1885
Western Grapeleaf Skeletonizer Moth, Western Grapeleaf Skeletonizer
Harrisina metallica is a day-flying in the Zygaenidae, commonly known as the . are deep metallic blue in color and exhibit -mimicry, resembling spider wasps in the family Pompilidae. The is found in the southwestern United States and northern Mexico. Larvae are specialized feeders on grape leaves and Parthenocissus species, skeletonizing foliage by consuming tissue between leaf . Caterpillars possess stinging hairs that can cause skin irritation or allergic reactions in humans.
Pronunciation
How to pronounce Harrisina metallica: /həˈɹɪsɪnə mɪˈtælɪkə/
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Identification
The deep metallic blue coloration of distinguishes Harrisina metallica from most other in its range. Its -like appearance may cause confusion with spider wasps (Pompilidae), but moths have two pairs of wings (wasps have one pair plus ) and typically rest with wings folded roof-like over the body. The can be distinguished from the eastern grapeleaf skeletonizer (Harrisina americana) by geographic range—H. metallica occurs west of the Mississippi River while H. americana occurs to the east. Larvae are recognized by their skeletonizing feeding damage on grape leaves and the presence of stinging hairs.
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Habitat
Associated with vineyards, riparian areas, and other supporting wild or cultivated grape (Vitis) and Virginia creeper (Parthenocissus). Occurs in arid and semi-arid regions of the southwestern United States.
Distribution
Southwestern United States from California to Texas, north to Colorado and Utah, and northern Mexico.
Seasonality
are active from April to October, with exact timing varying by location. Multiple may occur in warmer parts of the range.
Diet
Larvae feed on grape (Vitis spp.) and Virginia creeper (Parthenocissus spp.), skeletonizing leaves by consuming tissue between the while leaving the vein network intact. feeding habits are not documented in available sources.
Host Associations
- Vitis - larval food plantgrape
- Parthenocissus - larval food plantVirginia creeper
Life Cycle
Complete with , larval, pupal, and stages. Larvae are the damaging stage, feeding gregariously on plant foliage. Specific details of site and stage are not documented in available sources.
Behavior
are (day-flying), unusual for . They exhibit -mimicry in both appearance and . Larvae feed gregariously on leaves.
Ecological Role
Larvae function as herbivores on grape and related vines. The serves as prey for various natural enemies in vineyard . Stinging hairs provide defense against .
Human Relevance
Considered a pest of commercial grape vineyards, where larval feeding reduces crop yield by damaging foliage. The is susceptible to bacteria-based that are organically certified. Contact with larvae can cause skin irritation or allergic reactions due to stinging hairs.
Similar Taxa
- Harrisina americanaEastern grapeleaf skeletonizer; occurs east of the Mississippi River and replaces H. metallica in eastern North America.
- Pompilidae (spider wasps) H. metallica is a -mimic with similar metallic blue coloration; distinguished by wing structure and resting posture.
Misconceptions
The "grape worm" applied to larvae is misleading as these are caterpillars (larval Lepidoptera), not true worms.
More Details
Wasp mimicry
The is one of several zygaenid that mimic ; this is thought to provide protection from that avoid stinging wasps.
Type specimen
Original description by Stretch in 1885; type locality in California.