Butterflies and crab spiders

TitleButterflies and crab spiders
Publication TypeJournal Article
Year of Publication1953
AuthorsVoss EG
JournalThe Lepidopterists' News

Recently I happened to notice in the Bull. Brooklyn Ent. Soc. for 1921 (vol. 16: p. 97) E. L. Bell's observation of a specimen of Epargyreus tityrus (now = E. clarus) apparently perched unnaturally on a red clover flower, where it was subsequently found to be dead and in the grasp of a crab spider. There may well be other records in the literature of captures of butterflies by non-webspinning spiders, and I would add this note on three species found in such situations. My only specimen, as it happens, of Ancyloxipha numitor Fab. taken during nine seasons of collecting in Emmet County, Michigan, was found on July 8, 1946, along the gravelly shore of the Straits of Mackinac west of Mackinaw City, where it was first observed in a natural enough position on the common Ox-eye Daisy (Chrysanthemum leucanthemum var. pinnatifidum). Closer examination showed it to be dead and still clutched by a small crab spider. On August 26, 1952, collecting at Carlisle, Cumberland Co., Pennsylvania, I took two dead butterflies from spiders on Goldenrod (Solidago sp.). These were Libytheana bachmanii Kirt. and a female Polites mystic Scud. All three of these butterflies were in good fresh condition (could it be that they had recently emerged before capture?). In all three cases the spider appeared to human eyes to be well camouflaged--white on the white ray flowers ("petals") of the daisy and yellow on the Goldenrod. What might investigation into the ultraviolet vision of butterflies and "camouflage" effectiveness of these spiders indicate? As we raise these questions, we may repeat with further emphasis the amazement expressed in Bell's note that such strong-flying butterflies should be the victims of capture.