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Pollinators of dominant prairie angiosperms were collected in the summers of 1998 through 2001 and examined for pollen loads. Data were collected on a restoration site, Litzsinger Road Ecology Center (St Louis County, Missouri), and a relict site, Paint Brush Prairie (Pettis County, Missouri). Statistical analysis of floral foraging preferences was performed, using the chi-square test for independence, and shows nonrandom floral visitation by the major species of prairie bumblebees (Bombus, Apidae) at plant species (or plant species groups). The small, short-tongued Bombus impatiens exhibits preference for Culver's root (Veronicastrum virginicum), while the large, long-tongued Bombus nevadensis primarily visits wild bergamot (Monarda fistulosa). The intermediatesized prairie bumblebee, Bombus griseocollis, visits these plants but also composites in Echinacea and Liatris, thus displaying a generalist foraging strategy. The rare Bombus fraternus is strongly attracted to the flowers of milkweeds (Asclepias spp.). Bumblebees seldom visit rattlesnake master (Eryngium yuccifolium), which instead is strongly preferred by large and small species of sphecid wasps (tribes Bembicini and Philanthini, respectively). Many other smaller insects also visit these plants, and these smaller members of the above-described pollination guilds tend to be generalist foragers only on restorations. On remnants, however, some of the above-mentioned plants (as well as Penstemon spp.) are visited by oligolectic foragers that appear to be unable to move out of the remnants and colonize prairie restorations in the current landscape. The occurrence of large numbers of remnant-dependent prairie insects and the fact that prairie insect entomofaunas are poorly known are 2 strong arguments for the very great need for detailed, long-term studies of prairie insect biodiversity as well as concern for insects in restoration strategies. These pollinating insect populations do not use prairie grasses very much and are dependent on dicots. Thus insects and animals at higher trophic levels, such as prairie birds that feed their young on insects, are expected to be poorly represented in monocultures of prairie grasses. Such plantings might be called "prairie deserts," except that true deserts are remarkably rich in dicots, insects, and birds.