Euglossa dilemma

Bembé & Eltz, 2011

Dilemma Orchid Bee, Green Orchid Bee

Euglossa dilemma is a metallic green native to Central America and Mexico, recently naturalized in Florida since 2003. Originally misidentified as E. viridissima, it was recognized as a distinct cryptic in 2011 based on mandibular tooth count, genetic differentiation, and perfume chemistry. The species exhibits facultative eusociality, with females nesting either solitarily or in small social groups with reproductive division of labor. Males collect volatile aromatic compounds from diverse sources to create species-specific perfumes for . In Florida, it has successfully established in urban and suburban environments, demonstrating notable behavioral plasticity in nest site selection and foraging .

Dilemma Orchid Bee - Euglossa dilemma, Crocodile Lake National Wildlife Refuge, Key Largo, Florida - 01 by Judy Gallagher. Used under a CC BY 2.0 license.

Euglossa dilemma 243530252 by Guy Babineau. Used under a CC0 license.

Green Orchid Bee (Euglossa dilemma) (7406599274) by Bob Peterson from North Palm Beach, Florida, Planet Earth!. Used under a CC BY-SA 2.0 license.

Pronunciation

How to pronounce Euglossa dilemma: //juːˈɡlɒsə dɪˈlɛmə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from the cryptic sister Euglossa viridissima by three mandibular teeth in males (versus two in E. viridissima, with any third tooth in different position). Males of E. dilemma possess characteristic perfume compounds absent in E. viridissima, including specific isomers of HNDB (2-hydroxy-6-nona-1,3-dienyl-benzaldehyde) detected through electroantennography. Both sexes exhibit brilliant metallic green coloration with , growing to approximately 13 mm length. Females possess corbiculae () on hind legs and a functional sting; males have enlarged hind tibiae with specialized pits for storing perfume compounds. Dark translucent membranous wings and long distinguish it from superficially similar halictid sweat bees.

Images

Habitat

In native range: hot dry including degraded forests, pastures, parks, and gardens; less dependent on primary forests than most euglossine bees. In Florida: urban and suburban areas, tropical and subtropical environments, human-modified landscapes. Nests in diverse substrates including tree cavities, wooden structures, and human-made objects.

Distribution

Native to Central America from Rica to Mexico. Naturalized in southeastern United States since 2003, first detected in Broward County, Florida. Established in at least 12 Florida counties with highest abundance in southern Florida; documented in Palm Beach County, Brevard County, and expanding range expected throughout southern half of Florida.

Seasonality

Peak activity during warmer months in Florida; year-round activity in tropical native range. Seasonal abundance patterns documented with reduced activity in cooler periods.

Diet

Females collect nectar, pollen, and plant resins for nest construction and - provisioning. In Florida, females gather substantial pollen from Senna mexicana and nectar predominantly from Ruellia brittoniana and Tecoma stans; also observed feeding on Hamelia patens, Cheilocostus, Tradescantia pallida, and Datura. Males collect volatile aromatic perfume compounds from floral and non-floral sources including basil (Ocimum basilicum), Stemmadenia littoralis, rotten timber, wood oozing resin, and .

Life Cycle

Facultatively eusocial: females can establish solitary nests or form small social groups of 2-5 individuals. In social nests, one female performs all -laying while subordinate daughters (1-2, occasionally up to 4) remain in natal nest to forage and assist in care rather than dispersing to found independent nests. All females in social groups remain reproductively capable, though subordinates experience reproductive suppression via oophagy (egg consumption by dominant). Larger groups (4-5 individuals) exhibit increased reproductive inefficiency and behavioral conflict. Females construct nests of plant resin (), creating up to 20 ; each cell provisioned with pollen and nectar and sealed with an egg. Larvae develop within cells, pupate, and emerge as .

Behavior

Males exhibit specialized scent-collecting : gather volatile compounds from environment to concoct -specific perfume blends stored in hollow hind leg pouches, presented to females during involving wing-fanning to disperse fragrance. Females demonstrate considerable behavioral plasticity in nest site selection, utilizing diverse natural and human-made cavities. Subordinate helpers exhibit totipotency—capable of transitioning to foundress behavior, physiology, and patterns when social hierarchy is disrupted. Social groups characterized by true division of labor with subordinates performing foraging and nest maintenance while remains in nest.

Ecological Role

Important of angiosperms in neotropical region; crucial neotropical pollinator of conservation concern. In Florida, potential pollinator of introduced and native plants; may compete with native bees for floral and nesting resources. Absence of obligate orchid mutualism in introduced range—unlike many native euglossines, E. dilemma successfully reproduces without access to orchid fragrance sources, instead utilizing diverse alternative perfume compounds.

Human Relevance

Accidentally introduced to Florida, likely transported in wooden structures such as pallets from Mexico. Established expanding in urban and suburban environments. Subject of extensive scientific research due to its facultative eusociality, providing insights into evolutionary origins of social and transitions from solitary to social . Potential implications for pollination of ornamental and agricultural plants in subtropical United States.

Similar Taxa

Euglossa viridissimaCryptic sister ; distinguished by male mandibular tooth count (two teeth versus three in E. dilemma), position of any accessory tooth, microsatellite frequencies, and absence of characteristic HNDB perfume isomers present in E. dilemma males.
Augochloropsis spp.Halictid sweat bees with similar metallic green coloration; distinguished by shorter , different wing venation, and lack of specialized male hind leg perfume-collecting structures.
Eulaema spp.Larger orchid bees with similar and male perfume-collecting ; distinguished by larger body size, different color patterns often including yellow or brown markings, and different male mandibular .