Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes

Upcoming Events

See Moth submissions from National Moth Week 2023

Photos of insects and people from the 2022 BugGuide gathering in New Mexico, July 20-24

Photos of insects and people from the Spring 2021 gathering in Louisiana, April 28-May 2

Photos of insects and people from the 2019 gathering in Louisiana, July 25-27

Photos of insects and people from the 2018 gathering in Virginia, July 27-29

Photos of insects and people from the 2015 gathering in Wisconsin, July 10-12

Previous events


Species Petrophila bifascialis - Two-banded Petrophila - Hodges#4774

Moth - Petrophila bifascialis Moth? - Petrophila bifascialis Petrophila bifascialis Two-banded Petrophila - Petrophila bifascialis Moth - Petrophila bifascialis Petrophila bifascialis Moth ID - Petrophila bifascialis Petrophila bifascialis - Two-banded Petrophila - Hodges#4774 - Petrophila bifascialis
Show images of: caterpillars · adults · both
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Pyraloidea (Pyralid and Crambid Snout Moths)
Family Crambidae (Crambid Snout Moths)
Subfamily Acentropinae
Tribe Argyractini
Genus Petrophila
Species bifascialis (Two-banded Petrophila - Hodges#4774)
Hodges Number
Synonyms and other taxonomic changes
original combination Cataclysta bifascialis Robinson, 1869 (description)
* phylogenetic sequence # 143975
Explanation of Names
BIFASCIALIS: from "bi" (two) + "fascia" (band, bundle); refers to the bands across the median area of both wings, and is the origin of the suggested common name above
wingspan 11-24 mm (1)
TL ≈ 7-12mm (2)

FW whitish with broad brownish-orange band across median area, and 3 smaller bands at varying angles near apex; HW white with broad orange AM band, a bold black spot in the middle, and a line of large black spots along outer margin. See Heppner's description(3)
Peppery white FW with double brown median band and three angled dashes at apex. HW has row of black and silver spots along outer margin (2)
The oblong black discal spot on the HW is the most conspicuous field mark when the HWs are visible. When the HWs are not visible, identification can be a little trickier. In Texas and Oklahoma, Petrophila cappsi is very similar but has an open dark loop on the HW in place of the solid black oval; Capps' Petrophila is less likely to show a small dark discal dot on the FW at the upper end of the orange tornal bar, but this is variable.
Much of eastern North America: Nova Scotia to Ontario and Minnesota, south to Virginia, Tennessee, and Arkansas (sparse); common but seemingly disjunct population in Oklahoma, Texas, and northeast Mexico (iNaturalist).
The SCAN database shows records from Alabama and Mississippi but the species is apparently sparse to absent in most of the Southeast.
Larvae are aquatic, living in silken webs in fast-flowing streams.(4)
Adults rest on nearby vegetation during the day, become active at night, and are attracted to light..
Adults fly from late May to September.
Larvae feed on diatoms and algae scraped from rocks in fast-flowing streams.(1)(4)
As with most species in the genus Petrophila, females tend to have proportionally longer narrower wings than males. When perched, males tend to hold there wings open more often than females, revealing the diagnostic HW pattern.
See Also
Petrophila cappsi in Texas and Oklahoma, has an open loop on HW instead of solid dark spot. FW usually lacks a dark discal dot.
Petrophila fulicalis has 3 dark spots arranged in triangle on FW, dark speckling in the middle of HW and a thin dark line over the eyespots.
Petrophila canadensis: like P. fulicalis but FW has open whitish loops in postmedian area.
Internet References
pinned adult image by John Glaser, plus flight season and distribution (Larry Line, Maryland)
pinned adult image and photos of related species by Jim Vargo (Moth Photographers Group)
presence in Texas; list (Dale Clark, Texas)
presence in Florida; list (John Heppner, Florida State Collection of Arthropods)
presence in Ontario; list (NHIC; Ontario Ministry of Natural Resources)
Works Cited
1.Field Guide to Moths of Eastern North America
Charles V. Covell, Jr. 2005.
2.Peterson Field Guide to Moths of Northeastern North America
David Beadle and Seabrooke Leckie. 2012. Houghton Mifflin.
3.Synopsis of the genus Parargyracytis (Lepidoptera: Pyralydae: Nymphulinae) in Florida
John B. Heppner. 1976. The Florida Entomologist, volume 59, number 1.
4.A generic revision of the aquatic moths of North America: (Lepidoptera: Pyralidae, Nymphulinae).
W. H. Lange, Jr. 1956. Wasmann J. Biol., 14:59-144.