Synonyms and other taxonomic changes
Lophocampa roseata (Walker, 1868)
Restricted to western Oregon, western Washington, and southwestern British Columbia.
Jeremy contacted Libby Avis who sent him a pdf from the Entomological Society of BC, which has a description of the caterpillar of Aemilia roseata. The description of the 4th instar fits these caterpillars well.
ENTOMOLOGICAL SOCIETY OF BRITISH COLUMBIA
Proc. (1958), Vol. 5, DEC. 22, 1958, pg 28
Aemilia roseata Wlk. - 4th instar
Length: 20 to 25 mm.
Head: shiny, black with labrum white.
Body: velvet black above with a narrow white girdle at the juncture of the segments, mostly concealed by the tufts of short dense hairs that spread out to meet one another from their individual tubercles;
each tuft consisted of hairs of two or three colours, arranged in layers: white at the base, then black, and where there were three colours, yellow above and central;
along the dorsum were nine pairs of tufts, one pair per segment with a similar, smaller, yellow centred pair below the spiracular line. The rest were black and white;
Tl had a pair of forward pointing white pencils of long hairs,
and segments A8 and A9 had each a similar pair directed backwards.
The admixture of the predominating white and black gave an overall ash colour to the caterpillar, the yellow points breaking up the otherwise solid appearance.
Underside light fuscous, legs banded with black and white, zebra fashion, claspers pale dusky.
Tanna Knouse contributed a nice series here, raised on Fir branches: