Genus: Ceratina Latreille, 1802
Subgenus: Calloceratina, Catoceratina, Ceratina, Ceratinidia, Ceratinula, Chloroceratina, Copoceratina, Crewella, Ctenoceratina, Dalyatina, Euceratina, Hirashima, Lioceratina, Malgatina, Megaceratina, Neoceratina, Neoclavicera, Pithitis, Protopithitis, Rhysoceratina, Simioceratina, Xanthoceratina, Zadontomerus
Common name: small carpenter bees
Ceratina are slender, minute to medium-sized bees, usually with black, shiny integument, but some species can be bright green to blue or have red abdomens (Daly, 1973; Michener 2007). Most species have limited yellow to pale or cream colored markings on the head, legs, and pronotal lobes but some have extensive maculations on their bodies (Michener 2007). Ceratina have sparse pubescence that make them appear hairless from a distance, and they have reduced, almost absent, scopa (Michener 2007). They range in body length from 2.2–12.5 mm (Michener 2007).
(modified from Michener 2007)
Ceratina may be confused with other small bees with similarly colored integument and yellow maculations on the face such as Hylaeus, or bees in the tribe Allodapini (Daly 1973; Michener 2007). Ceratina can be separated from these similar-looking genera by the forewing, which has three sub-marginal cells (Michener 2007).
Ceratina are polylectic and have been found visiting flowers from plant genera in a number of different families including Anacardiaceae, Apiaceae, Araliaceae, Asteraceae, Cynareae, Brassicaceae, Boraginaceae, Campanulaceae, Chenopodiaceae, Convolvulaceae, Dipsacaceae, Euphorbiaceae, Fabaceae, Lamiaceae, Liliaceae, Malvaceae, Oleaceae, Plumbaginaceae, Scrophulariaceae, Simaroubaceae, Tamaricaceae, Resedaceae, Rosaceae, Rutaceae, and Vitaceae (Daly 1973; Mitchell 1962; Terzo and Rasmont 2011).
Ceratina nest in pithy stems or twigs, which they excavate and build their nest cells inside (Michener 2007). Their nest cells are unlined with partitions between cells made of loosely held together pith particles (Michener 2007). Most species are solitary, but in some species the nest may be occupied by two or more, usually related, females that have been shown to exhibit some division of labor (Michener 2007).
Ceratina includes more than 300 described species (Michener 2007).
Four species have been documented as invasive in the U.S.
Ceratina (Ceratinula) arizonensis has been inadvertently introduced from North America into Hawaii. It was first reported on Oahu in 1950 and has since established and spread to other Hawaiian islands (Hirashima 1971a).
Ceratina (Euceratina) dallatorreana, which is originally from the Mediterranean region, was first reported in California in 1949 where it is now established (Daly 1966). This species reproduces by thelytokous parthenogenesis; only females have been found in the U.S. (Daly 1966).
Ceratina (Neoceratina) dentipes and Ceratina (Pithitis) smaragdula are native to Southeast Asia and are thought to be invasive throughout the South Pacific. They have been introduced and have established populations in Hawaii and were likely introduced somewhat recently through shipping traffic (Shell and Rehan 2017; Shell and Rehan 2019).
Ceratina has a cosmopolitan distribution and can be found on every continent; however, the genus is rare and limited in distribution in Australia (Michener 2007).