The caterpillar of the Ribbed Case Moth (Hyalarcta nigrescens), live and pupate in a silken case. In the first few instars, the case may have some sparse bits of other matter attached to the casing. As the caterpillar grows, the casing will become quiet bare with several longitudinal ribs.

Case Moth (Family Psychidae), Alice Springs, NT
Ribbed Case Moth (species Hyalarcta nigrescens, family Psychidae), Alice Springs, NT

The following early instar below of the Ribbed Case Moth (Hyalarcta nigrescens) was photographed in Alice Springs, Northern Territory (17 December 2021). The above instar of the Ribbed Case Moth was also photographed in the same garden in Alice Springs (3 March 2022).

The male moth of the Hyalarcta nigrescens has a hairy head and body (usually black or brown), with pale hairs around the head and tuft of yellowish hairs on the tip of the abdomen. With a wingspan about 2.5 cms, the forewings of the male moth are transparent, with the hindwings being variously blue, black or brown.

Many thanks to Leonie Kirchmajer of the Entomology Australia “Invertebratology” Facebook group for IDing the early instar species Hyalarcta nigrescen.

Also many thanks to iNaturalistAU members for IDing this Hyalarcta nigrescen.

Ribbed Case Moth (Hyalarcta nigrescens), Alice Springs, NT
Ribbed Case Moth (Hyalarcta nigrescens) on the glass of a building, Alice Springs, NT

Check out our page on the variety of types of Case Moths.


  • Scientific classification
  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Hexapoda
  • Class: Insecta
  • Informal: Pterygotes
  • Order: Lepidoptera
  • Family: Psychidae
  • Genus: Hyalarcta
  • Species: Hyalarcta nigrescens

Footnote & References

  1. Hyalarcta nigrescens (Doubleday, 1845), Atlas of Living Australia, https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:810e0f87-63ad-4f0a-81ea-80508ee82da8
  2. Photos of Ribbed Case Moth Hyalarcta nigrescens, iNaturalist, https://www.inaturalist.org/taxa/492081-Hyalarcta-nigrescens/browse_photos
  3. Hyalarcta nigrescens, Australian Moths Online, CSIRO, https://moths.csiro.au/species_taxonomy/hyalarcta-nigrescens/
  4. Ribbed Case Moth – Hyalarcta nigrescens, Brisbane Insects and Spiders, https://www.brisbaneinsects.com/brisbane_casemoths/RibbedCaseMoth.htm

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