Synanthedon resplendens

Synanthedon resplendens, also known as the sycamore borer moth, is species of a clearwing moth native to western North America.[1][2] Larva of this moth live under the bark of sycamore, ceanothus, coast live oak,[3] and, on rare occasions, avocado trees.[4] Sycamore hosts include California sycamore, Arizona sycamore, and American sycamore trees.[2] Coast live oak is a confirmed host, but this moth likely uses many or most other western oaks as well.[5]

Sycamore clearwing moth
Sycamore clearwing moth nectaring on wild buckwheat, San Bernardino County, California, May 2022
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Sesiidae
Genus: Synanthedon
Species:
S. resplendens
Binomial name
Synanthedon resplendens
Hy. Edwards, 1881
Synonyms

Albuna resplendens

Description

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Adult

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The coloration of the adult moths mimics the coloration of a vespid wasp.[3] Their movements may also be reminiscent of wasps, with "intermittent rapid running and fluttering of wings".[6]

Adults are mostly yellow with black markings on the thorax and abdomen.[3] Sycamore borer moths typically have a brownish black[3] or bluish black[6] head and antennae, yellow palpi, and a yellow collar, with a blue-black thorax that has nearly parallel yellow lines on the sides.[6]

This moth's wings are mostly transparent, with yellow- to orange-colored borders.[3] The forewings have iridescent blue-black veins and yellow scales on the apical cells; the hindwings are completely transparent with brownish black fringes and inner yellow scales.[6] The wingspan of the moth is about 18–24 mm (0.71–0.94 in) across.[3][6]

This species is sexually dimorphic; females are larger than males.[2]

Eggs, pupae, larvae

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Egg color is gold[3] or pink.[2] The eggs are about .8 mm (0.031 in) long, ovoid, and have a slightly reticulated (net-like) appearance or texture.[6]

Pupae are about 10 mm (0.39 in), are found in white to brownish silken cocoons, and are a "shining mahogany brown".[6]

Larvae are pinkish to whitish and reach 18 mm (0.71 in) in length; the head is reddish brown.[3]

Life cycle

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One generation occurs per year.[3] Adults emerge and are on the wing from May through early August, with greatest emergence in June and July.[3]

 
Sycamore clearwing, Sonoma County, California, June 2021

The adults only live for about a week,[2] during which time the ovoid, gold-colored eggs are laid singly on the bark in small cracks or depressions.[3] Old or slow-growing trees and injured tissues are favored sites for egg laying and feeding.[3] Larvae rarely damage the cambium or feed in the wood.[3] Pupae are formed just below the bark surface, and protrude through the bark when the adult is ready to emerge.[3] Larvae mine the bark below the surface, producing numerous serpentine feeding tunnels.[3][6] Reddish sawdust-like frass, which larvae expel from tunnels, accumulates in branch crotches or on the ground below the infested area.[3] The outer bark surface over the tunnels becomes roughened after repeated infestations and may produce wet ooze.[3] Larval galleries are most often around the base and the lower trunk of the tree, but may be found in branches up to 9 m (30 ft) above the ground.[6] The tunnels can extend over 100 cm2 (16 sq in).[3] Overwintering occurs as larvae or pupae within the bark tunnels.[3]

 
Larva expel reddish frass from the bark galleries

Pupal skins may be visible in emergence holes.[3] Emergence holes are round, 3 mm (0.12 in)[3] to 6 mm in diameter, and in oak trees are found exclusively in bark cracks.[7]

Geographic range

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The sycamore clearwing moth is found throughout California,[6] into the north as far as Yukon,[8] and at least as far east as New Mexico.[6] The ceanothus clearwing, Synanthedon mellinipennis, overlaps somewhat in range[3] and uses a similar catalog of host plants.[9]

Impact

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According to the University of California Integrated Pest Management program, "Sycamores tolerate extensive boring by this insect, and generally no control is recommended."[10] According to the U.S. Forest Service, even though the superficial damage to trees by this species may be deemed unsightly "the amount of damage caused by this insect is generally considered to be of minor importance".[3]

References

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  1. ^ "Sycamore Borer Moth (Synanthedon resplendens)". iNaturalist. Archived from the original on 2022-09-26. Retrieved 2024-03-17.
  2. ^ a b c d e Kenmuir, Sylvia (n.d.). "Sycamore Borer" (PDF). Department of Entomology SciLit (entomology.unl.edu). University of Nebraska at Lincoln. Archived (PDF) from the original on 2021-04-27. Retrieved 2024-03-17.
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w Swiecki, Tedmund J.; Bernhardt, Elizabeth A. (2006). A Field Guide to Insects and Diseases of California Oaks. Pacific Southwest Research Station (Report). Gen. Tech Rep. PSW-GTR-197. Albany, California: U.S. Forest Service Treesearch Department. pp. 70–71. doi:10.2737/PSW-GTR-197.   This article incorporates text from this source, which is in the public domain.
  4. ^ "Sycamore Borer Synanthedon resplendens (Edwards, 1881)". Butterflies and Moths of North America (www.butterfliesandmoths.org). Archived from the original on 2024-03-17. Retrieved 2024-03-17.
  5. ^ "Sycamore Borer Moth, Synanthedon resplendens". calscape.org. Archived from the original on 2024-03-17. Retrieved 2024-03-17.
  6. ^ a b c d e f g h i j k Solomon, James D. (1995). Guide to Insect Borers in North American Broadleaf Trees and Shrubs. Southern Hardwoods Laboratory, Southern Forest Experiment Station (Report). Handbook AH-706. Stoneville, Mississippi: U.S. Forest Service Treesearch Department. pp. 72–75. Archived from the original on 2024-03-17. Retrieved 2024-03-17.   This article incorporates text from this source, which is in the public domain.
  7. ^ Haavik, Laurel; Coleman, Tom; Flint, Mary; Venette, Robert; Seybold, Steven (2014-03-21). "Densities of Agrilus auroguttatus and Other Borers in California and Arizona Oaks". Insects. 5 (1): 287–300. doi:10.3390/insects5010287. ISSN 2075-4450. PMC 4592623. PMID 26462589.
  8. ^ Nelson, Tyler D.; Cu, Kristoferson; Gibson, Joel F.; Needham, Karen M.; John, Esme; Judd, Gary J. R.; Moffat, Chandra E. (2023-12-30). "An annotated checklist of clearwing moths (Lepidoptera: Sesiidae) in British Columbia and Yukon Territory". Journal of the Entomological Society of British Columbia. 120. ISSN 1929-7890. Archived from the original on 2024-01-17. Retrieved 2024-03-17.
  9. ^ "Ceanothus Borer Moth, Synanthedon mellinipennis". calscape.org. Archived from the original on 2024-03-17. Retrieved 2024-03-17.
  10. ^ "Clearwing Moth Management Guidelines--UC IPM". ipm.ucanr.edu. Archived from the original on 2023-01-23. Retrieved 2024-03-17.