Other Common Names
Angulated Cutworm (larva)
Synonyms and other taxonomic changes
Syngrapha rectangula (Kirby, 1837)
Plusia rectangula Kirby, 1837
Autographa rectangula
Plusia mortuorum Guenée, 1852
Syngrapha rectangulata ab. demaculata Strand, 1917
Autographa rectangula r. nargenta Ottolengui, 1919
* phylogentic sequence #931227
Explanation of Names
Modern Latin "rectangular" from rectus- "straight, upright" + angulus- "angle"
Numbers
Common throughout most of range.
Size
wingspan 30-35 mm (Covell, 1984)
(1)
forewing length 14-17 mm (Pogue, 2005)
(2)
larva length to 25 mm
Identification
Adults - forewing dark gray to black with extensive white or silvery areas; subterminal line black, jagged; stigma large, irregular, white or silvery, often connecting to pale basal patch; fringe checkered black and white; hindwing dirty pale brown with broad blackish terminal band and pale fringe.
Larvae - body green with pale stripes of varying width; head yellowish-green; wide dark green middorsal stripe bordered by broad white stripes of about same width; narrower white subdorsal stripe; mostly yellowish white spiracular stripe; minute black spots circle segments, but visible mainly between subdorsal and spiracular stripes; spiracles white; prolegs only on abdominal segments 5, 6, and 10 [adapted from description by C.T. Maier et al].
Syngrapha abstrusa,
alias,
cryptica and
rectangula cannot be reliably separated using DNA barcoding, PLoS ONE 12(6): e0178548; Supplementary Table S8
(3). Examiantion of genitalia is usually required.
"Syngrapha rectangula is easy to identify in most of its range because of the large amount of silvery shading - except near the West Coast where it has a dark form that looks a lot like alias and often needs to be dissected to be sure.
In the Smithsonian there were about 150 S rectangula from the Maritime Provinces and Maine and they were sorted into the typical silvery form and a darker form (with much less silver, especially near the wing base. On dissection, it turned out that the "dark form" were all S cryptica... Syngrapha cryptica was described exclusively from Michigan and Wisconsin - highly disjunct from the Maritime populations. We have since found it in Ontario and Quebec. The East Coast populations of cryptica look a lot like rectangula, but there is less silver, and often there is a rounded dark patch in the terminal area about 1/3 from the top. The Ontario and Great Lakes form of cryptica looks very different, but the genitalia are the same, but maybe they're different species - the coastal form has not been barcoded, but it looks like that wouldn't help anyways, so best to stick to the genitalia and call them geographic forms. The inland form has brown shades in the forewing and the silvery areas, especially in the basal area, have a definite greenish tone, so they are relatively easy to pick out - especially after you've seen a real one in the flesh..." - C. Schmidt & D. Lafonataine (pers. comm., 03/5/2018)
Range
Across southern Canada from Newfoundland to British Columbia, plus adjacent northern states, south in the west to California, south in the east (mountains only) to North Carolina and Tennessee (Pogue, 2005).
(2)Habitat
Wet boreal and montane coniferous forests; adults are often active during the day but are also nocturnal and come to light.
Food
Larvae feed on various Pinaceae, but prefer balsam fir (
Abies balsamae) and western hemlock (
Tsuga heterophylla) (Pogue, 2005).
(2)Life Cycle
One generation per year; overwinters as a larva.
Remarks
Considered a pest because it feeds on economically important conifers, but is a solitary defoliator and rarely causes extensive damage.
See Also
In the west, Syngrapha surena forewing pale areas are less irregular and gray, not white. Other species of Syngrapha have less white on forewing.
Print References
Eichlin, T. D. & H. B. Cunningham 1978. The Plusiinae (Lepidoptera: Noctuidae) of America north of Mexico, emphasizing genitalic and larval morphology. USDA Tech. Bulletin 1567: 1-122 (
PDF)
(4)
Lafontaine, J. D. & R. W. Poole 1991. Moths of America North of Mexico, Fascicle 25.1: p.116; pl.3.39-41
Pogue, M. G. 2005. The Plusiinae (Lepidoptera: Noctuidae) of Great Smoky Mountains National Park. Zootaxa 1032: 1–28 (
PDF)
(2)Internet References
www.forestpests.org Caterpillar picture and description (C.T. Maier
et al, USDA Forest Service, forestpests.org)
Macromoths of Northwest Forests and Woodlands photo and description of adult, other information (Jeff Miller, USGS).
distribution map plus taxonomic history, foodplants, references (Markku Savela, FUNET)
pinned adult image (Canadian Forest Service)
presence in California; list (U. of California at Berkeley)
distribution in Canada list of provinces (U. of Alberta, using CBIF data)
