University of Alberta Museums Search

This smallish geometrid has a pale tan ground colour with heavy brown markings, consisting of antemedian (AM) and postmedian (PM) lines, dark marginal shading, discal spots and (usually) black marginal blotches. Probole are best recognized by the extended outward tooth-like projection of the forewing PM line. More localized and less common than P. alienaria. Virtually identical to (and previously considered to be conspecific with) P. alienaria. The distinguishing character in wing markings is the angle of the PM line above the "tooth"; it is perpendicular to the wing margin where it meets the edge in alienaria, while in amicaria the line is directed more toward the wing apex, and is essentially perpendicular to the anal (not the costal) margin. Some have treated P. alienaria and amicaria as forms of the same species (eg. McGuffin 1987). Ferguson (in Hodges 1983) treats them as separate species, and according to Handfield (1999), alienaria is a generalist feeder on deciduous shrubs while amicaria feeds only on species of dogwood (Cornus). There also appear to be differences in the male antennal structure among some populations, at least in eastern North America (Handfield 1999). This interesting situation certainly warrants further research in Alberta