Very little is known about the arthropods associated with the wild ancestors of agricultural crops. Given that wild relatives of crop plants are subjected to human pressures of habitat loss and transgene flow, baseline levels of arthropod biodiversity and community composition are urgently needed to detect declines associated with anthropogenic disturbance. Here, we sampled arthropod abundance and community composition on the wild ancestor of cultivated rice, Oryza rufipogon Griffiths, in the Mekong Delta of Vietnam to ask: 1) Do arthropods associated with O. rufipogon fluctuate temporally and spatially in terms of community composition, diversity, and abundance? 2) What is the abundance and diversity of lepidopteran and hemipteran species associated with O. rufipogon across sites and seasons? We found a total of 578 arthropod taxa, distributed across 178 families in 17 orders. Rarefied species richness and arthropod abundance did not vary across the sampled stands of O. rufipogon, but did vary across the years. Arthropod abundance and metrics dependent upon abundance generally declined over the observation period, suggesting that the sampling effects or other unobservable factors may have contributed to the decline in the arthropod community. Overall, predators dominated the community composition, followed by detritivores and herbivores. Predatory and herbivorous taxa were the most speciose guilds. We found 45 unique taxa of Lepidoptera, many of which were previously undescribed on rice. Given that wild relatives such as Oryza rufipogon support a diverse arthropod community, this study provides a baseline evaluation of the arthropod community in this important native habitat.