College of Science and Health Theses and Dissertations


Elizabeth Shafer, DePaul University


Residential yards in urban areas can be effective in supporting pollinators when native flowers are grown (Lepcyzk et al., 2017). One pollinator, the Rusty Patched Bumble Bee (Bombus affinis), is an endangered bee whose population has declined over 87% in the last 20 years. As a combination of a collection and conservation project, I created an organization called the Evanston Host Plant Initiative and coordinated 275 individuals to grow any of the 37 native host plants known to support the Rusty Patched Bumble Bee (FWS & DOI, 2018) and use iNaturalist to inventory plants and bees in Evanston, Illinois. I ground truthed all host plant observations made before 2021, and determined a 96% proportional presence. I surveyed Rusty Patched Bumble Bee host plants on the landscape and observed the largest number of host plants in the South Evanston, contrasting with the iNaturalist records that portrayed the largest number of host plants in North Evanston. I created maps of the iNaturalist host plant data, and conducted Kernel Density analyses for each blooming period that depicted the same three hot spots of host plants in North Evanston at two public parks and Northwestern University. My Buffer Zone analysis illustrated that Evanston has coverage of host plants, and most of the landscape was within 0.6 miles of a host plant, meeting the approximated maximum foraging distance of the Rusty Patched Bumble Bee. In 2021, there was a 116% increase in host plants on iNaturalist and a 70% increase in iNaturalist observers of host plants in Evanston. There was also a 116% increase of bees on iNaturalist and a 114% increase of iNaturalist observers of bees, but there were no documented sightings of the Rusty Patched Bumble Bee in Evanston. Out of 155 people who responded to a social survey I designed, most (128; 83%) grew host plants for the Rusty Patched Bumble Bee, and some (27; 17%) uploaded photos of plants and/or bees to iNaturalist. The majority of survey respondents (127/153; 83%) self-identified as enthusiastic gardeners and environmentalists (128/151; 85%), and 70% (109/155) did not previously know about the Rusty Patched Bumble Bee.