Abstract Halyomorpha halys (Stål), the brown marmorated stink bug or BMSB, has become a major pest and nuisance since it arrived in the U.S. in 1996. This insect can feed on approximately 200 different plant species, many of which are important ornamental crops. BMSB's preference for fruits and the damage they cause is known, but it is not known how their presence on non-fruiting woody ornamentals can impact vegetative growth. The first study confined adult BMSB to branches of established stock block trees of five plant species for one month. Four measurements were taken to assess plant growth: branch length, leaf area, number of leaves, and dry weight. The second study confined adult BMSB on seedlings of eight plant species for one or two months. In this study, the same four measurements were taken as well as the change in trunk diameter. Overall, there were no significant differences in plant growth and only some marginal differences between branches or seedlings caged with BMSB versus no BMSB (control) after one or two months. Adults laid eggs on all plants species in both trials, and nymphs were observed to develop to the 2nd instar stage in the seedling trial on all the plant species except for maple. Confinement of BMSB on branches of well-established nursery plants or on newly planted seedlings had little or no impact on growth over a two month exposure. Index words: Halyomorpha halys, Hemiptera, ornamentals, seedling, vegetative growth. Species used in this study: Brown marmorated stink bug (Halyomorpha halys Stål); Dolgo crabapple (Malus sp.); Yoshino cherry (Prunus yedoensis Matsum.); Japanese elm (Ulmus davidiana Planch.); Siberian elm (Ulmus pumila L.); Ginkgo (Ginkgo biloba L.); Washington hawthorn (Crataegus phaenopyrum (L.f.) Medik); lsquo;Ivory Silk' lilac (Syringa reticulata Blume); ‘Green Mountain' silver linden (Tilia tomentosa Moench); ‘Crimson Sunset' maple (Acer truncatum Bunge); ‘Franksred' maple (Acer rubrum L.)