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Species Pero morrisonaria - Morrison's Pero - Hodges#6755

Pero morrisonaria Pero morrisonaria Northern Thorn? - Pero morrisonaria Morrison's Pero, 6755 - Pero morrisonaria Morrison's Pero - Hodges#6755 - Pero morrisonaria Geometridae (Morrison's Pero) - Pero morrisonaria Pero morrisonaria  - Pero morrisonaria Pero - Pero morrisonaria
Show images of: caterpillars · adults · both
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Geometroidea (Geometrid and Swallowtail Moths)
Family Geometridae (Geometrid Moths)
Subfamily Ennominae
Tribe Azelinini
Genus Pero
Species morrisonaria (Morrison's Pero - Hodges#6755)
Hodges Number
6755
Synonyms and other taxonomic changes
Pero morrisonaria (Hy. Edwards, 1881)
Azelina morrisonaria Hy. Edwards, 1881
* phylogenetic sequence #199225
Explanation of Names
Named in honor of H. K. Morrison, who collected the specimen Edwards described.
Size
Wingspan 34-40 mm.
Larvae to 35 mm.
Identification
Adult: forewing heavily mottled with black and brown; discal spot white or pale yellow; PM line with shallow sinus near midwing; outer margin scalloped. Hindwing light gray with pale-bordered dark median line, row of small black terminal dots, and scalloped outer margin.

Larva: an excellent twig mimic; body variably yellowish and brownish with dark middorsal stripe and scattered dark warts; head angular, dark brown, with light brown swollen lobes and light brown streak across front; inconspicuous pair of narrow meandering dark brown subdorsal stripes; spiracles dark brown; third abdominal segment with prominent spiracular swelling and large dark tubercle below [adapted from description at forestpests.org].
Range
Newfoundland to British Columbia, and coast to coast in northern United States, south in the east to South Carolina, south in the west to California.
Habitat
Coniferous and mixedwood forests; adults are nocturnal and attracted to light.
Season
Adults fly from May to July.
Larvae from July to September; pupation occurs in September.
Food
Larvae feed on conifers [Balsam Fir (Abies balsamea) and other firs in the west, Douglas-fir (Pseudotsuga menziesii), hemlock, pine, spruce, tamarack] but have also been reported on broad-leaved trees and shrubs [alder, birch, buffaloberry, meadowsweet, poplar, willow].
Life Cycle
One generation per year; overwinters as a pupa in soil or debris.
See Also
P. ancetaria is similar but, in Canada, occurs only in Ontario and Quebec (compare images of both species).

Separating Pero honestaria, ancetaria, and morrisonia - Jason D. Roberts
In honestaria, the PM area of the forewing is generally much less mottled than in ancetaria and morrisonia, with an almost nonexistent ST line (usually clearly seen as jagged/toothed and white in the other two). The FW median band of honestaria also, at the bottom 3rd, makes a straight, somewhat basad trajectory to the inner margin, whereas in the other two it has a tooth-like indent (as it crosses the anal vein). Honestaria also lacks the black spot near the midpoint of the FW outer margin, that may or may not be present on the other two. On the hindwing of honestaria, the PM line touches nearly the middle of the anal margin, whereas in the other two the PM line nearly reaches the anal angle. Finally, honestaria usually has smoother wing margins that are not serrated in appearance.
Now ancetaria and morrisonia are more difficult to separate, but generally morrisonia is much more mottled in overall appearance and often has a more deeply serrated appearance of its wing margins, particularly the HW outer margin. Also, in my experience, morrisonia often has some pale spots near the FW apex that I have not seen firsthand in any ancetaria specimens. But honestaria is usually the easiest to distinguish. Of course individual variation is always a factor.
Print References
Edwards, Hy. 1881. Descriptions of some new species of Heterocera. Papilio 1(7): 121
Internet References
adult images (Larry Line, Maryland)
description of adult plus habitat, food plants, flight season, biology, distribution (Strickland Entomological Museum, U. of Alberta)
live larva image plus description, food plants, seasonality, biology, life cycle (C.T. Maier et al, USDA Forest Service, forestpests.org)
presence in South Carolina; county map (John Snyder, Furman U., South Carolina)
presence in California; list (U. of California at Berkeley)
distribution in Canada list of provinces (CBIF)