none. USA,-Maine. Crab spiders (Misumena vatia , Thomisidae) selected leaves of common milkweed (Asclepias syriaca ) over those of spreading dogbane (Apocynum androsaemifolium ), pasture rose (Rosa carolina ), and chokecherry (Prunus virginiana ) as nest-sites in pairwise experiments among these four substrates. Nesting success was higher on milkweed than on the other three plant species. Early survival of the clutches was thus correlated with the preferences exhibited by their mothers. The major source of nest failure was parasitization by the ichneumonid wasp, Trychosis cyperia , which accounted for over 50 per cent of the nest losses.