Beat cloth sampling and pitfall traps were used to compare the diversity and abundance of canopy and ground dwelling Araneae and Opiliones in treated and untreated alfalfa seed, alfalfa hay, and feral alfalfa. The mean number of Araneae collected from alfalfa hay, treated and untreated alfalfa seed and feral alfalfa was significantly different in both beat cloth and pitfall traps samples (P=0.0001) and (P=0.0001) respectively. The mean number of Opiliones collected in pitfall traps also differed between sites (P=0.0001). A Shannon-Weaver diversity index (H’) based on beat cloth samples show feral sites were the most diverse, and had the highest Araneae species richness. A Shannon-Weaver diversity index (H’) of the pitfall trap catches shows that treated and untreated alfalfa seed sites had higher H’ values, due to greater species evenness in these sites.

Overall, alfalfa grown in an agricultural setting has a lower abundance and diversity of Araneae in the plant canopy compared with plants growing in feral sites. Based on the results from treated and untreated alfalfa seed, insecticide application alone is not limiting Araneae. Tillage may be an important factor in comparing ground-dwelling species. Pitfall trap catches of Araneae and Opiliones were highest in alfalfa hay which has a more stable soil environment compared to alfalfa seed fields. Feral alfalfa growing in abandoned fields and along roadsides is not tilled, however, other factors such as a lack of moisture may also limit ground dwelling species.