Other Common Names
the common name of "September Thorn" given at
U. of Alberta is not recommended because a European species (
Ennomos erosaria) is already well known by that name (
1,
2)
Synonyms and other taxonomic changes
Synaxis pallulata Hulst, 1896
The genus Synaxis is synonymized with Tetracis, Ferris and Schmidt, 2010
Numbers
one of 13 species in this genus in North America
Identification
Adults: Ochreous, varying in color across individuals. FW apex falcate. DFW irrorated with darkscales; with very dark brown (nearly black) AM and strongly-developed PM lines; PM line broadly paleshaded outwardly; the degree to which PM line angles inwardly at M3 varies across individuals; MB colored as rest of wing, or only very slightly darker. DHW with well-developed dark median line that fades out toward upper margin. Dark discal spots on FW and HW well-developed. Ventrally paler with dorsal markings lightly repeated. Some females tend to be much darker in hue than males.
Larva: a twig mimic at rest; head light brown with dark markings; body color variable from yellowish-cream to brownish-gray to reddish-brown; second thoracic segment swollen dorsally; paired tubercles near posterior margin of fourth, fifth, and eighth abdominal segments[adapted from description at Canadian Forest Service]
Range
Southern California north to British Columbia, eastward to Idaho (Clearwater Co.) and western Montana (Lewis and Clark Co.) from near sea level to 7200’ (2200m).
Habitat
coniferous forests in western mountains
Season
adults fly from August to October
larvae from June to August
Food
Larval hosts are members of Cupressaceae and Pinaceae - Abies concolor, Picea englemanni, Tsuga heterophylla, Picea sitchensis, Abies grandis, Pseudotsuga menziesii and Tsuga canadensis.
Life Cycle
overwinters as an egg; one generation per year
See Also
in
Synaxis jubararia the forewing AM and PM lines are usually farther apart and not as heavy, and the overall color is generally paler (see images of
S. jubararia and
S. pallulata at All-Leps, and
compare images of both species at CBIF)
Synaxis cervinaria forewing lacks dark speckling, has straight PM line, and the moth flies in spring; the larvae of
S. jubararia and
cervinaria feed only on broad-leaved trees and shrubs, whereas the larvae of
S. pallulata are conifer-feeders
Large Maple Spanworm (
Prochoerodes lineola) forewing PM line is sharply bent toward base near costa
Tetracis pallulata generally can be separated from other ochreous species in this genus by the presence of pale shading distad and dark shading basad of the PM line.
Internet References
adult description plus habitat, flight season, biology, foodplants, distribution (Strickland Entomological Museum, U. of Alberta)
live larva images plus biology, foodplants, description, biology (Canadian Forest Service)
presence in Utah; list (Joel Johnson, Utah Lepidopterists Society)
presence in California; list (U. of California at Berkeley)
