Genus: Anthidium Fabricius, 1804
Subgenus: A. (Proanthidium) Friese, 1898
Species: Anthidium oblongatum (Illiger, 1806)
Common name: none
Anthidium (Proanthidium) oblongatum are black bees with yellow markings (Hoebeke and Wheeler 1999; Michener 2007). Males and females range in body length from 8–11 mm (Hoebeke and Wheeler 1999). Anthidium oblongatum is a non-native species in the U.S. and Canada.
Anthidium oblongatum can easily be distinguished from all other Anthidium (s. str.) species in the U.S. by its lamellate pronotal lobe and scutellum. Females can be distinguished by the medially concave margin of T6 and large number of mandibular teeth (9–12 teeth). Males can be readily identified by the median apical projection on T6 and the bilobed T7 (Gonzalez and Griswold 2013).
Anthidium oblongatum adults have been recorded in flight from May to September, with peak activity occurring from June to August (Gonzalez and Griswold 2013).
Anthidium oblongatum is associated with xerophilic vegetation (Hoebeke and Wheeler 1999), and is a generalist that has been observed collecting pollen and nectar from Crassulaceae, Fabaceae, Scrophulariaceae, and Resedaceae (Westrich 1990; Maier 2009). It appears to favor pollen from Lotus corniculatus, Onobrychis viciaefolia, and Sedum reflexum (Westrich 1990; Müller 1996). Additionally, A. oblongatum have been observed collecting from the flowers of various weeds in urban restoration sites and landfills (Hoebeke and Wheeler 1999). In the U.S., A. oblongatum can often be found visiting Senecio cineraria (Miller et al. 2002).
Anthidium oblongatum nests in dry, warm habitats (Hoebeke and Wheeler 1999). Nests are constructed in hollowed out cavities in soils, bricks, stonewalls, railroad embankments, weathering slopes, and rocks as well as in excavated thistle and Umbelliferae stems (Westrich 1990; O’Brien et al. 2012; Onuferko et al. 2015). Anthidium oblongatum typically use the hairs from Stachys germanica and S. byzantina (Lamiaceae), Verbascum (Scrophulariaceae), and Helichrysum and Echinops ritro (Asteraceae) as nesting materials (Hoebeke and Wheeler 1999). Each nest has up to eight cells (Hoebeke and Wheeler 1999).
This species is of special interest because it is both invasive, and the first species of Anthidium to be documented entering the nest of another bee, Bombus impatiens (Graham 2018). The night temperatures leading up to the discovery of A. oblongatum in the nest of B. impatiens were uncharacteristically low, so it is possible that the A. oblongatum were attempting to find a warm place to reside at night (Graham 2018). However, if A. oblongatum were inside the hive in order to rob resources, this could cause a negative impact on the native bee population. More research is needed in order to determine the motivation behind the nest intrusion (Graham 2018).
Anthidium oblongatum occur throughout most of southern and temperate Europe, and was accidentally introduced to the U.S. in the 1990s (Russo 2016). They have since spread throughout the eastern and midwestern part of the U.S. in Maryland, New York, New Jersey, Pennsylvania, Ohio, Illinois, Connecticut, and southern Canada (Hoebeke and Wheeler 1999; Miller et al. 2002; Romankova 2003; Michener 2007; Maier 2009; Tonietto and Ascher 2009).