Genus: Hoplitis Klug, 1807
Subgenera: Alcidamea, Anthocopa, Chlidoplitis, Eurypariella, Formicapis, Hoplitis, Jaxartinula, Kumobia, Megahoplitis, Micreriades, Pentadentosmia, Platosmia, Proteriades, Robertsonella, Stenosmia, Tkalcua
Common name: mason bees
Hoplitis range in body length from 3–18 mm and range in body form from slender and elongate to robust (Michener 2007). Hoplitis are generally nonmetallic, apart from a few common North American species which can be vibrantly metallic green (Michener 2007).
Hoplitis contains approximately 360 described species in 16 subgenera worldwide (Michener 2007; Sedivy et al. 2013). Nearly 60 species in 11 subgenera are found within the United States (Ascher and Pickering 2016; Wilson and Carril 2016). In general, bees are more diverse in desert habitats; however, Hoplitis are more diverse in boreal and cool mountain habitats (Wilson and Carril 2016).
(modified from Michener 2007)
Hoplitis may be confused with Osmia due to similar body shapes and the presence of the lateral tooth of male T6; however, Hoplitis can be differentiated by the characteristics listed above (Michener 2007).
Hoplitis anthocopoides was accidentally introduced into Albany County, New York in the 1960s (Eickwort 1970; Wilson and Carril 2016) via host plant introduction. Hoplitis anthocopoides is native to Europe and can be found as far north as Scandinavia and as far south as Greece (Eickwort 1970). Hoplitis anthocopoides is dependent on Echium vulgare and Anchusa officinalis, which are introduced weeds commonly found in disturbed sites such as roadsides (Eickwort 1970). They build their nests on the surface of rocks using mortar and pebbles, which are rarely used by native bees (Eickwort 1970). Due to the abundance of their host plants and accessible nesting sites, H. anthocopoides will likely extend its range throughout eastern North America (Eickwort 1970).
Plant host preferences are species dependent. Several Hoplitis species are generalists, and will visit any blooming plant. Other species select plants within multiple families such as Fabaceae and Boraginaceae, or specialize on a single plant family such Hydrophyllaceae, Fabaceae, or Boraginaceae. A few species are dependent on a single plant genus, such as Phacelia, Acmispon, Hosakia, Larrea, or Penstemon (Wilson and Carril 2016).
Species within the subgenera Penteriades and Proteriades specialize strictly on Cryptantha. Penteriades and Proteriades have hooked bristles on their proboscis that allows them to harvest pollen located in the narrow flower tubes (Müller 2006; Michener 2007). The bee then moves the pollen from the bristles on the proboscis to the abdominal scopa for transport to the nest (Müller 2006).
Hoplitis are solitary bees. Nesting habits are species specific and diverse, ranging from nesting in excavated burrows in soil, cracks in rocks, or pithy plant stems to pre-existing abandoned beetle, wasp, and bee burrows, empty galls, and empty snail shells (Wilson and Carril 2016). Hoplitis will use specific materials such as leaf pulp, pebbles, masticated leaves, bits of wood, resin, clay, sand, and petals to create partitions between cells and nest plugs (Michener 2007). Materials are used alone and in combination with one another, depending on the species or subgenus (Michener 2007). For example, species within the subgenera Alcidamea and Formicapis build nests in pithy stems, and use leaf pulp, pith particles, and/or pebbles to create the walls between cells (Michener 2007). Further, species within the subgenus Anthocopa create short burrows in the soil with each burrow ending in a single cell. They line cells with brightly colored petals and pack the upper portion of the burrow with mud (Michener 2007).
Hoplitis is one of the largest and most wide-ranging genera of Osmiini (Michener 2007; Wilson and Carril 2016). They are found on every continent except Australia, South America, and Antarctica (Sedivy et al. 2013). Within the U.S., Hoplitis are more diverse along the west coast than the east coast. However, some species (e.g., H. anthocopoides) are found exclusively in the east, whereas others (e.g. H. robusta) occur throughout North America (Wilson and Carril 2016).