Flower preference and hoverfly diversity in pollinator gardens

Pollinating insects assist in the pollination of many flowering plants including the produce we consume. Hoverflies are a diverse group often overlooked in North American research. They rely on nectar, pollen, and aphids for development. We wanted to determine if pollinator gardens affect hoverfly diversity and which flower varieties they prefer. We hypothesized that pollinator gardens provide a diverse range of floral resources, increasing hoverfly diversity and that flower color and ease of nectar access affect floral use. Hoverflies were collected during 4 sampling periods in each of 3 years at 2 sites. Floral observations on 71 m2 plots of 70 flower varieties were observed for 15 minute intervals to determine hoverfly visitation rates. New collection methods were implemented for hoverfly collection in 2021 including netting of hoverflies for later identification and following hoverfly feeding flights for data on their preferred flowers to forage. We collected 92 total hoverflies of 5 different species in pan traps. The pollinator garden showed higher abundance of hoverflies than the nearby lawn at the more established site, however, there was no significant difference at the less established site. We observed 216 hoverfly visits to flowers, and we saw that hoverflies only visited 26 of the 70 available flower varieties. Our results suggest that pollinator gardens increase hoverfly abundance and they prefer warm colored flowers with easily accessible nectar and pollen. Hoverflies can be a great benefit to our native plants, gardeners, and even farmers who may want to attract both pollinators and predatory insects.