Chauliognathus pensylvanicus (De Geer) and C. marginatus (Fabr.) are two of the most common species of cantharid beetles observed in agroecosystems in Virginia. Despite their widespread abundance and early recognition and description in the 1700s, little is known about their phenology and ecological role in agricultural systems. Immatures have been recorded feeding upon soft-bodied insects such as lepidopteran larvae, and adults frequently visit flowering plants, where they eat nectar and/or pollen. Beyond those observations, relatively little is known about these species, which are conspicuous elements on and around farms, though there is considerable potential for their use as pollinators and predators in a biological pest control context. I employed a phenological study to determine the period of C. marginatus activity in Southwestern Virginia, and found adults active on a variety of flowers from mid-May to late July. On these flowers, they spent a large percentage of their day mating or feeding, with significant differences in the percentage of beetles participating in behaviors based on time of day and beetle sex, but not based on month. The majority of C. marginatus observations occurred on narrowleaf mountain mint (Pycnanthemum tenuifolium Schrad.), poison hemlock (Conium maculatum L.), and wild bergamot (Monarda fistulosa L.). I also used a community science-based approach to evaluate the usage of host plants and flower colors by C. marginatus and C. pensylvanicus. Chauliognathus marginatus utilized white flowers more than expected based on their potential availability, while C. pensylvanicus utilized yellow flowers over all other flower colors and more than expected based on their potential availability. Communities of flowers available to and observed with C. marginatus and C. pensylvanicus differed significantly at the family and genus levels. Laboratory bioassays supported these conclusions regarding C. pensylvanicus color preference, but not C. marginatus color preference. Lastly, because of their susceptibility to nontarget chemical exposure in agroecosystems, I tested the efficacy of both organic and conventional vegetable insecticides against C. marginatus adults. The highest mortality was seen in the acetamiprid, flupyridifurone, sulfoxaflor, and imidacloprid treatments, which reached 97-100% mortality at two days after treatment. High mortality (60-97% two days after treatment) was also seen in the organic treatments containing azadirachtins, pyrethrins, and Chromobacterium subtsugae strain PRAA4-1T. Mortality in the Burkholderia spp. strain A396 and spinosad treatments was not significantly different from that of the controls, however, control mortality was relatively high in both assays. / Doctor of Philosophy / Soldier beetles are common but underappreciated members of many ecosystems across the world. Two species are seen especially frequently on or around farms in Virginia: the margined leatherwing and the goldenrod soldier beetle. These beetles are active during different periods of the year (spring and fall, respectively), and adults gather in large numbers on flowering plants and may be beneficial pollinators of some flower species. Their immatures are stealthy and typically crawl along the ground, but may climb into crop plants to eat pest insects. Because of these potential roles in pest management, we studied their yearly activity, preferences in flower types and colors, and their susceptibility to chemical insecticides that are commonly used in vegetable crops. Margined leatherwing adults were active on wildflowers and flowering weeds from mid-May to late July. While they were on these flowers, they spent most of their day mating and feeding. Most of the observations we made were on narrowleaf mountain mint (a native perennial wildflower), poison hemlock (a toxic biennial invasive weed), and wild bergamot (a native perennial wildflower). I was interested in determining what flowers and flower colors each soldier beetle was found most frequently on throughout their entire range, so we used community science data collected from iNaturalist to evaluate those questions. Margined leatherwings were found much more often on white flowers than flowers of any color, and more than I expected based on the proportion of white flowers blooming in the spring. Goldenrod soldier beetles were found much more often on yellow flowers, and more than I expected based on the proportion of yellow flowers that bloom in the fall. The types of flowers blooming for each of these two species were different, as well as the types of flowers they visited. Our results were partially supported with a laboratory experiment where beetles had to choose colored panels to escape an enclosure; the goldenrod soldier beetles chose the yellow panel a great majority of the time, but the margined leatherwings did not choose the white panel as much as we expected. These differences in color and flower preferences are interesting and should be explored further. Finally, I tested several organic and conventional (non-organic) insecticides against margined leatherwing adult beetles to see how they would react if incidentally exposed in a farm setting. Insecticides of both types caused considerable mortality over two days, though two of the products we tested seemed not to have major negative effects on the beetles. This experiment was difficult because it seems that margined leatherwings are sensitive to being contained to experimental chambers, and many died without being exposed to any insecticide at all. In summary, these beetles are important, unique, and interesting, and deserve more study, especially regarding their potential role in agricultural pest management. These studies are some of the first to explore the behavior, host plants, and insecticide tolerance of these common soldier beetles, but will hopefully inspire others to look deeper into their biology in the future.

The potential control of cucumber beetles, Acalymma vittatum (Fab.) and Diabrotica undecimpunctata howardi (Barber)(both Coleoptera: Chrysomelidae) two major pests of cucurbits, was assessed in a cucurbit agroecosystem by using buckwheat (Fagopyrum esculentum Moench) border habitat to attract the natural enemies, Celatoria diabroticae (Shimer) and Celatoria setosa (Coquillett) (both Diptera: Tachinidae) and Chauliognathus pennsylvanicus (Deg.) (Coleoptera: Cantharidae). Five different plants were seeded in the border and buckwheat dominated. Four natural enemy groups were also included as indicators of the attractiveness of the floral border: The Order Diptera; the Families Tachinidae and Syrphidae of Diptera; and the Order Hymenoptera. In 1995-1996, rows of squash, Cucurbita pepo (L.) var. melopepo (Alef.) ‘Seneca Prolific’, and cucumbers, Cucumis sativa (L.) ‘Arkansas Littleleaf’, were planted perpendicular to floral border habitats. Sticky traps and modified Malaise traps on transects at intervals from the border were used to monitor insect numbers. Insect counts and yields of cucurbits were analyzed using analysis of variance with contrasts for linear and quadratic effects and regression model fitting. Borders were strongly attractive to Diptera and moderately attractive to C. pennsylvanicus, Syrphidae, Tachinidae, and Hymenoptera. C. setosa and C. diabroticae counts were too low to analyze and borders habitats did not have any meaningful effect on yields. The border conserved populations of Diptera, leatherwings, Hymenoptera, and tachinids on some dates and may be useful with economic thresholds for pest management because of an observed gradient of insect movement. / Master of Science