First Advisor

Susan Masta

Date of Award


Document Type







Bees -- Behavior -- Oregon -- Portland, Animal-plant relationships, Botanical gardens -- Oregon -- Portland




Solitary native bees are known to be diverse, but are not well studied in Oregon. In order to identify the bee genera present in the Leach Botanical Garden, and their floral usage, a survey was conducted over 2020 and 2021. Biweekly sampling was used to collect bees on flowers, in order to obtain floral usage data. Bees were identified to genus with published taxonomic keys. In total, 19 genera of bees were found. Bee abundance fit a normal distribution, and peaked in July. Ceratina and Lasioglossum were a significant proportion of the population, and were present in the garden from April to September. Megachilidae, especially Osmia, was relatively abundant in April and May. Halictidae was a significant part of the summer and fall bee population. The vast majority of bee genera surveyed were found to be generalists, utilizing many flowers across multiple plant families. Asteraceae was by far the most utilized plant family, with Solidago and Symphyotrichum being highly visited genera. Overall, Leach was found to contain a highly diverse bee population, utilizing a wide array of flowering plants. Asteraceae was found to be a good choice of flower to attract high numbers of bees to a garden space, however early season bees must also be considered in choosing plants.


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An undergraduate honors thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Biology with Biology Department Honors.

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