Genus: Euglossa
Euglossa bees live mainly in Central and South America.
Euglossa is a genus of bees that are typically found in North, South, and Central America near the equator. There are about 130 Euglossa species in total 1. These bees only have a few hairs on their body, which allows us to see the beautiful metallic colouration of their exoskeletons. These bees come in a variety of colours from metallic green, blue, purple, and bronze. These bees range in size from 8mm up to 18mm making them small or medium sized bees depending on the species 2. These bees also have very long tongues in order to reach nectar within narrow tube-like flowers. Euglossa rugilabris is one of the orchid bees with the longest tongue which is 28mm in length; that's twice as long as its body! These bees are commonly known as orchid bees because Euglossa males visit orchids. Euglossa males form specialist relationships with orchid flowers and are sometimes the only pollinator for a specific orchid species. Just like many other bees, orchid bees refers to more than one bee genera, so I will be referring to these bees as Euglossa bees.
Euglossa mainly feed on pollen and nectar from plants. this makes them both palynivores (which is an animal that eats pollen) and nectarivores (an animal that eats nectar). Pollen provides Euglossa with protein and fat, and nectar provides them with carbohydrates in the the form of sugar and starches. Euglossa don't collect nectar in large quantities, so they don't make honey. Euglossa only provision a small amount of pollen mixed with nectar, which makes a paste, for their developing young.
Euglossa bees collect pollen, nectar, and more from a wide variety of plants. Euglossa bees collect pollen and nectar from a wide variety of flowers, not just orchids 3 4. A couple of Euglossa species are noted to collect resin from a flowering plant known as Dalechampia. The resin these bees collect will be used to create the bee's nests. The resin shapes the nest as well as creating a waterproof shell which protects the bee's growing young. Euglossa males are known to collect a wide variety of fragrances. They get these fragrances from plants, fruit, feces, fungi, even chemicals like DDT to create their own perfume 4. They have specialized structures on their front legs and their hind legs to collect and store these stinky compounds.
This photo is of the dilemma orchid bee (Euglossa dilemma). This picture shows a female orchid bee. You can tell it is a female orchid bee because it has a groove in it's hind leg which is used to carry pollen. These bees are usually only about 13 mm in length. Euglossa in general are very fast fliers and can sting (though they do it very rarely). These bees have very long tongues which are used to lap up nectar from deep fluted flowers.
Euglossa dilemma was introduced into south Florida. In Florida, it is able to collect all of the resources it needs from non-orchid flowers and plants. Basil is one important plant for Euglossa dilemma males as they are able to obtain vital scent compounds that they normally derive from orchid flowers 5.
Euglossa females create resin nests for developing young.
Euglossa bees collect plant resin from plants such as Dalechampia, cashew trees, and conifer trees for nest construction 4. Plant resin is a substance that is thick in its viscosity and hardens when exposed to air (it's what amber is made out of). Euglossa bees collect this resin so they can construct their nests.
Some Euglossa create their nests within cavities, while others create exposed aerial nests 6. Cavity nests can typically occur within wood and within enclosed holes in the ground. Some of the more unique cavity nests Euglossa have been recorded creating are within plant roots, termite nests, cacao fruits, bamboo nodes, and in active nests of vertebrates or social insects 6 7. Within these cavity nests, Euglossa females line the cavity and construct cells to hold developing young with resin. Aerial nests are constructed completely with plant resins. These nests have been found attached to trees, stems, twigs, and the underside of leaves. These nests are typically spherical or tear drop shaped.
Most Euglossa species are solitary, but some live communally and others have some social behaviours. Solitary bees are those species in which each female will mate with a male, create a nest, provision brood cells with food, and lay eggs within brood cells 6. There are some species which are more communal where several females will use and reuse nests and cells that have already been created. Some Euglossa species have been noted to have some social behaviours. These behaviours include one female, who is usually a mother or sister to the other females in the nest, laying eggs, staying within the nest, and suppressing the reproductive capacity of other females in the nest by eating their eggs 7.
This photo shows an aerial nest of Euglossa hyacinthina. This nest is made up entirely of resin. In photo A, you can see an unfinished aerial nest hanging off of a branch 8. The dark area in the center of the structure is where the nest is attached to the branch. The white arrow in this photo is pointing to stored resin globules within the nest. Photo B shows the same nest the next day with two more layers of resin built up. And photo C shows the nearly completed nest. Photo C was taken three days after photo A.
To build this nest, the orchid bee would forage for resin to create the resin globules seen in photo A. She would then take a small amount of resin and place it on the edge of the structure. The thicker bands of resin you can see on the nest are where the new resin was placed. The bee would then shape the placed resin to create the thinner part of each resin band. She then repeats this process until the nest is complete. This nest was built by only one female and likely only took her about 6 days!
"File:Interior view of a nest of Euglossa hyacinthina under construction - JHR-029-015-g001A.jpeg" by Wcislo D, Vargas G, Ihle K, Wcislo W (2012) is licensed under CC BY 3.0.
"File:Interior view of a nest of Euglossa hyacinthina under construction - JHR-029-015-g001B.jpeg" by Wcislo D, Vargas G, Ihle K, Wcislo W (2012) is licensed under CC BY 3.0.
"File:Interior view of a nest of Euglossa hyacinthina under construction - JHR-029-015-g001C.jpeg" by Wcislo D, Vargas G, Ihle K, Wcislo W (2012) is licensed under CC BY 3.0.
Male Euglossa mating behaviours.
Euglossa males display several mating behaviours to attract a mate, but the most unique of these is creating a personalized perfume. Before mating, male Euglossa will spend time collecting various scent compounds and storing these various compounds in a specialized structure 9. The structure is essentially a spongy pouch on the back legs of male Euglossa with an opening. The scent compounds these males collect come from many sources. The most unique of these scent compounds come from, as their common name suggests, orchid flowers. Many orchids produce volatile compounds collected by male orchid bees, but don’t produce nectar or abundant pollen that could attract other pollinators. There is an estimate that about 10% of Central American orchid species are pollinated by male euglossines (euglossines are the group of all orchid bees which). Male Euglossa bees have also been recorded collecting plant sap, fungi, mammalian feces, and even collecting the perfume from living and dead male Euglossa.
After males have collected these scent volatiles, they find a small place in which they can land and perch such as twigs, leaves, or stems of plants. At these perches, males engage in display flights in which they release their perfume. These display flights typically look like the males are zig-zagging, hovering, or circling in the air above their perch and using their legs to spread the perfume collected within their hind legs 10. At these perches, other males may approach and initiate male-male interactions during the display bouts. These interactions rarely involve physical contact and usually end with one of the males leaving the perch and the other resuming their display at the perch site where the encounter took place 11. There is evidence that other males are also attracted to other male Euglossa perfume. When a female chooses to mate with a male, she will only mate once which makes Euglossa functionally monogamous.
"Catasetum barbatum 009" by Dalton Holland Baptista is licensed under CC BY-SA 3.0.
This photo shows an orchid species that only Euglossa bees have been recorded visiting. This orchid is commonly known as the bearded orchid (Catasetum barbatum). It is unique in that it has male, female, and hermaphroditic flowers 12. This species belongs to a group of flowers that throws it's pollinarium at its Euglossa pollinators. A pollinarium is plant structure that contains a mass of pollen, usually a stalk, and an adhesive disk that sticks the pollen structure to insect pollinators when they interact with the flower.
Euglossa bees are so important to these orchids as their size is essential in assuring that pollinarium transfer from male to female flowers occurs 13.
A Euglossa species of note.
Within Biology, the naming of new species is storied. Scientists who discover new species may name that species after themselves, after another person, or even after pop culture references. Euglossa bazinga is a species of Euglossa that was named after a catchphrase said by the character Sheldon Cooper on "The Big Bang Theory", an American television sitcom 14. Sheldon uses the word 'Bazinga' when he is tricking someone or pulling a prank. This name is a perfect representation of this bee because we used to think Euglossa bazinga was another similar species of bee (Euglossa ignita), but was realized as its own species in 2012.
This collage shows 9 different species of Euglossa males. Euglossa are one group of bees that have bright metallic colouration and come in all sorts of colours from red to purple. These photos also show the length of some of their tongues. These tongues are all fairly long and didn't even fit in the photo in the case of Euglossa igniventris (Photo A). Pictures are not to scale.
A) Euglossa igniventris B) Euglossa hansoni C) Euglossa dodsoni D) Euglossa tridentata E) Euglossa heterosticta F) Euglossa championi G) Euglossa hemichlora H) Euglossa viridissima I) Euglossa cybelia
Euglossa are invaluable for orchid pollination
Euglossa bees have been shown to be generalist pollinators that need certain scent volitiles to create perfumes for mate attraction. Unfortunately, there is very little data on Euglossa health, abundance, and biodiversity. There is evidence that these bees are on the decline along with other types of bees 16.
In addition to their own health, abundance, and biodiveristy, the decline of Euglossa bees could lead to the decline of wild orchid flowers. There are orchid species that are pollinated specifically by male Euglossa bees because the male Euglossa use their scent volatiles in their perfumes 13. These orchids do not have nectar or pollen to give to bees and some are very specialized in that they need bees of a certain size for pollination. Because these types of orchids don't have any floral rewards, they do not attract other bees and would not survive.
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Author: Melissa Platsko
Date published: December 15, 2023
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