Etainia thoraceleuca

Distinguished from other North American Etainia by genitalia morphology and DNA barcodes. The only other native American Etainia species is E. arctostaphylos, also feeding on Ericaceae. E. thoraceleuca is sister to the European E. albibimaculella, from which it differs genetically and in host associations. Adults collected at light; larvae identified by short leafmines on Arbutus or Arctostaphylos with subsequent stem boring.

Small moth typical of Nepticulidae (microlepidoptera). Adult morphology described in original description; specific external features not detailed in available sources. Male and female genitalia characterized for species diagnosis.

Low Pinus ponderosa forest on ridges; oak-juniper-pine woodland; various California habitats including nurseries, planted trees in Sonoma and Marin Counties, and natural stands of Arbutus and Arctostaphylos.

USA: California (Marin, Sonoma, Contra Costa, Del Norte, Lake, Los Angeles, Madera, Mendocino, Riverside, San Bernardino, San Diego, Santa Barbara, Siskiyou, Yuba, Colusa, Santa Clara, Tulare Counties), Arizona (Cochise, Yavapai Counties); Canada: Ontario (Almonte, Ottawa area, Lambton County); likely Washington State based on unconfirmed leafmine records.

Adults active May through October based on light trap collections. Larvae collected March-April. Holotype emerged late May from larva collected mid-March.

Leaves, stems, and branches of Arbutus and Arctostaphylos species (Ericaceae). Larvae make short leafmines on host foliage, then continue feeding in stems and branches.

• Arbutus arizonica - hostHolotype reared from this species
• Arbutus menziesii - hostNative Pacific madrone
• Arbutus unedo - hostStrawberry tree
• Arbutus × 'Marina' - hostHybrid ornamental; used as trap plant for monitoring
• Arctostaphylos uva-ursi - hostKinnikinnick; damage observed in Washington State
• Arctostaphylos spp. - hostBroad-leaf manzanita species; specific identifications sometimes uncertain

Four larval instars observed. Larvae make short leafmines on host plants, then bore into stems and branches. Pupation occurs in cocoons in duff beneath host plants, approximately 5 cm deep, usually between fragments of dead leaves. Adults emerge from May to October. Holotype emerged 24 May 1987 from larva collected 19 March 1987.

Larvae are leafminers and stem borers, causing visible damage to host plants. Adults attracted to light. Can be collected using trap plants (Arbutus 'Marina') with emergence funnels and netting enclosures.

Herbivore and pest of Ericaceae in native ecosystems and horticultural settings. Causes leaf spotting and shoot dieback on host plants. Potential pest of native Arbutus menziesii and cultivated Arbutus species.

Pest in California nurseries and on planted ornamental trees; damage first reported in 2014 from Marin County nurseries. DNA barcoding used to link larval damage to adult specimens, demonstrating utility of molecular methods for identifying cryptic pest species.

• Etainia arctostaphylosOnly other native American Etainia species; also feeds on Ericaceae but differs in host range and distribution
• Etainia albibimaculellaEuropean sister species; differs genetically and in geographic range and host associations

• Nepticulidae
• leafminer
• stem borer
• Ericaceae
• pest
• North America
• California
• Arizona
• Ontario
• Arbutus
• Arctostaphylos
• microlepidoptera

• BugGuide
• iNaturalist taxon
• NCBI Taxonomy
• A new North American species of Etainia (Lepidoptera, Nepticulidae), feeding on Arbutus and Arctostaphylos species (Ericaceae)