The brown marmorated stink bug, Halyomorpha halys (Heteroptera: Pentatomidae), is a recently introduced insect pest from Asia that has become established in the United States. It is polyphagous and damages a number of economically important crops in China, Taiwan, Korea, and Japan, including many fruits, soybean, Paulownia tomentosa (a valuable timber tree in Asia), and other economically significant plants in its native range. Existing literature consists largely of reports where H. halys has been noted on crops, but there is very little information on its actual host plant range and biology in nature. In addition, there is hardly any information on this pest’s ecology and behavior in Asia. The objective of this study was to observe H. halys throughout a summer field season in Beijing, China, in botanical gardens planted with trees on which the stink bug has been observed, and determine its use of different host plants in its native range. From late June to mid-August, a variety of plants, both known hosts and other nearby tree species, were surveyed with beat sheet and sweep net in Beijing and the life stage, number of H. halys, and host plant were recorded. Host use by different life stages of the stink bug is relevant, as it indicates development of generations through the summer field season, which may be used by researchers collecting H. halys. Parasitism of egg masses of H. halys by hymenopteran parasitoids was also recorded.