Stink bugs (Pentatomidae) and parent bugs (Acanthosomatidae) of Ontario and adjacent areas:
A key to species and a review of the fauna
CJAI 24 September 1, 2013
doi:10.3752/cjai.2013.24

S.M. Paiero¹*, S.A. Marshall¹, J.E. McPherson², and M.-S. Ma¹. 

¹School of Environmental Sciences, University of Guelph, Guelph, ON, N1G 2W1
²Department of Zoology, Southern Illinois University, Carbondale, IL, 62901
*Corresponding Author

Introduction
The recent arrival of the Brown Marmorated Stink Bug [Halyomorpha halys (Stål)] in eastern North America (Hoebeke & Carter 2003) has highlighted the need for an updated and user-friendly key to the Pentatomidae to facilitate swift and reliable identification of this serious new pest in threatened areas of the northeast. The province of Ontario, one such threatened area, is home to dozens of superficially similar pentatomoid bugs, most of which can be identified to species using keys to the northeastern North American Pentatomidae by McPherson (1982). Those keys, while functional, are illustrated only with simple black and white line drawings of specific characters and emphasize technical characters that require microscopic examination. The purpose of the current project is to provide an updated key, taking advantage of a digital format to make extensive use of colour photographs that render the keys more reliable and user-friendly. Two key formats, a simplified key and a complete key, are provided. The simplified key allows rapid identification of species using characters visible with a hand lens or on photographs of the dorsum and venter of the bug taken with a good camera. Although it will work for the great majority of routinely encountered stink bugs, some unusual colour variants and uncommon species could be misidentified using the simplified key. The second key is a complete key requiring the examination of more technical characters, many of which are only visible with a microscope. This complete key, an updated version of McPherson’s (1982) key, should allow for confident determination of all species in our region.

Although the main incentive for developing these keys was to render one newly introduced pest unequivocally identifiable, they also cover all Ontario Pentatomidae and the superficially similar Acanthosomatidae. These families include several species of potential conservation concern, several beneficial predaceous species, and many phytophagous species. Good pentatomoid keys are needed for students and workers in a variety of disciplines including biological control, pest management, and biodiversity studies. Recent faunal studies for other regions in North America include the following: Washington (Zack et al. 2012), North Dakota (Rider 2012), Michigan (Swanson 2012), Illinois (McPherson 1982), Kansas (Packauskas 2012), and Missouri (Sites et al. 2012).

The keys presented here include 56 species, 53 of which belong to the family Pentatomidae (stink bugs) and three of which are in the family Acanthosomatidae (parent bugs). Of these 56 species, 50 are currently known from Ontario, and the remaining six are northeastern species that could occur in Ontario. Of those species known from Ontario, three were first recorded from the province in the last decade (Paiero et al. 2003, Fogain and Graff 2011) and one (Trichopepla atricornis Stål) is recorded here from Ontario for the first time. An additional species, Amaurochrous ovalis Barber & Sailer, was erroneously recorded in Canada by Paiero et al. (2003) based on misidentified material of A. cinctipes. Thyanta custator (Fabricius), now treated as the subspecies T. custator custator (Fabricius), is not included because its occurrence in Canada is suspect. Rider and Chapin’s (1992) revision of Thyanta treated T. custator custator as a southeastern coastal plain species, and we have seen no material from Ontario that would indicate otherwise. Other recent nomenclatural changes include the following: Cosmopepla bimaculata (Thomas) is now treated as C. lintneriana Kirkaldy (McDonald 1986), Holcostethus piceus (Dallas) as H. macdonaldi Rider & Rolston (Rider & Rolston 1995), and Hymenarcys aequalis (Say) as Mcphersonarcys aequalis (Say) (Thomas 2012). Apateticus bracteatus (Fitch) and A. cynicus (Say) are now in the genus Apoecilus (Thomas 1992). Acrosternum hilare (Say) and A. pensylvanica (Gmelin) are in the genus Chinavia (e.g., Rider 2012). The updated checklist of Ontario stink bugs given here reflects the tribal placements given in Rider (2012) and Thomas and Brailovsky (1999).

The distributions summarized in the species pages are based on McPherson (1982), Froeschner (1988), and Maw et al. (2000), with the addition of recent records (Paiero et al. 2003, Fogain and Graff 2011).