Understanding the source of insects within an agricultural production system is essential to selecting the most suitable management practices. In this thesis, I examine the spatial patterns of arthropods in Michigan commercial celery systems and evaluate whether field margins are sources of insects therein. Insect abundance was measured at different distances within six different celery fields located in southwest Michigan during 2013 and 2014. Most herbivores were evenly distributed throughout the field, although minor edge effects were detected when overall abundance was low. Herbivore abundance in margins, relative to the field, varied across groups; tarnished plant bugs and leafhoppers are key pests that may be using margins for habitat. Most predators were evenly distributed across the field. Syrphid flies were more abundant in margins, suggesting greater association with these areas than other groups. Parasitoid abundance was also consistently margin-centric across groups during both seasons. In 2014, I performed a mark-capture experiment in which three field margins were sprayed with a protein marker. Arthropods were subsequently captured and tested for the presence of the protein. Most groups had at least one individual testing positive for the presence of the marker, but the majority of specimens in every group tested negative. Variation in mark percentage, as well as the spatial distribution of marks, showed that some groups, such as tarnished plant bugs and syrphid flies, utilize the margins more than others. Any systematic change in the way growers manage their margins would likely affect these groups to a greater degree than the other groups in the study.
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