Alsophila pometaria By Matt Young January 8, 2018 12:00 MST Photograph by Mark Sturtevant. Photography contest, Honorable Mention. Alsophila pometaria – inchworm. Like other caterpillars, this Geometrid (inchworm) larva has “prolegs” on its abdomen. Prolegs are not generally regarded to be homologous to true legs. Most inchworm species have secondarily lost several of their prolegs in comparison to other caterpillars, but some species have not completed this process. About 1/3 the way from the rear end of this one are a vestigial pair of prolegs.