Data from: To provide pollinator nesting habitat, cut dead perennial stems in their first winter

Pollinator habitat management has traditionally focused on floral
resources, but the stems of flowering perennial plants could also provide
nesting and overwintering resources for solitary bees and wasps. Seasonal
vegetation management therefore risks destroying nesting or overwintering
insects. In residential pollinator gardens, gardeners receive conflicting
advice—with little evidence base—about when dead plant stems can be
removed without disrupting nesting or overwintering pollinators. To
address this knowledge gap in a mesic temperate climate, we conducted
participatory research in which volunteers provided stem samples from
their gardens, sampling cohorts of dead stems through winter, spring,
summer, and fall. We received a total of 2,879 stems, representing 75
samples from 20 gardens in four ecoregions. This dataset documents the
sampled stems and their insect residents, and includes results of a
volunteer experience survey conducted at the end of the project. Overall,
37 stems were occupied by living insects, and eight contained evidence of
recent occupants, representing at least 12 species of solitary bees and
wasps dominated by the genus Ceratina. Winter stems—those that had been
alive and uncut in the previous growing season—were not occupied. Although
the overall occupancy rate was low, our results verify that stems of
perennial plants in residential gardens provide nesting and overwintering
resources. Trimming (but not removing) stems in their first winter is the
management practice that would maximize this resource for pollinators
without disturbing its occupants.