By Leah Brooks
It would be impossible to talk about pollinators without talking about bees, one of the only types of pollinators that actively collect pollen. Bees are a diverse group of insects with over 4,000 distinct species in North America alone. Northeastern North America is home to approximately 450 different species, and more than 200 native bee species have been recorded in the state of Delaware. North American bees have been divided into six families, including Andrenidae, Apidae, Colletidae, Halictidae, Megachilidae, and Melittidae. Read on to learn about the different bee families and some interesting examples of each one.
Andrenidae includes miner bees in the Andrena genus, one of the largest genera of native bees, with over 1,300 species worldwide. They are commonly found foraging at spring ephemeral flowers growing in woodlands. Many Andrena species are pollen specialists and only collect pollen from certain flowers. Miner bees are solitary ground nesters and construct nests that look like small anthills. In fact, most of our native bees are solitary, in contrast to the social non-native honeybees which famously live in hives. For solitary bees such as miner bees, a lone female will build or locate a nest in which to lay her eggs, then collect and store pollen for the subsequent larva –all without assistance.
Apidae contains several prominent North American bee species, such as the large, fluffy, slow-flying bumble bees (Bombus species), as well as long-horned bees (genera Eucera and Melissodes) characterized by the long, thin antennae of the males. Cuckoo bees (Nomada species), which primarily lay eggs in the nests of miner bees (Andrena), are also classified in this family, as are both large and small carpenter bees (genera Xylocopa and Ceratina, respectively). The eastern carpenter bee (Xylocopa virginica) is a common sight in gardens. Like bumble bees, carpenter bees are large, but they are distinguishable by their shiny, hairless abdomens. Male carpenter bees have a yellow faceplate whereas females have a completely black face. In the spring, females build nests in wood and usually nest in social groups of two to five.
Plasterer bees (Colletes species) are also called cellophane bees due to the method of smoothing the walls of their nest cells with plastic-like secretions that dry into a cellophane-like lining. Many are pollen specialists, and all are solitary nesters. Mt. Cuba Center hosts Delaware’s only recorded population of the summer cellophane bee (Colletes aestivilas), which only collects pollen from alumroot flowers (Heuchera species). Lucky visitors may observe them foraging from straight-species American alumroot (Heuchera americana) along the Upper Dogwood Path in late May-early June.
Masked bees (Hylaeus species) are small, black and yellow bees that ingest and carry pollen internally in a special structure inside their stomach called a crop, rather than transporting pollen externally on hairs or via pollen baskets. They regurgitate the pollen into the nest cell where it serves as food for the growing larva. Like other members of this family, masked bees seal the provisions with a cellophane-like barrier. Masked bees usually create nests in dead stems or other naturally occurring cavities.
Members of this family are commonly known as sweat bees due to their attraction to human perspiration. These bejeweled green or blue-green metallic bees are pollen generalists, and are common in open, suburban habitats. Metallic sweat bees (Lasioglossum species) form one of the largest genera in North America.
Both leafcutter and mason bees are members of the Megachilidae. Leafcutter bees (Megachile species) cut pieces out of leaves and use them to build cigar-shaped nests in cavities. Mason bees (Osmia species) are named for their propensity to use “masonry” materials, such as mud, when building their nests. They tend to make their nests in small cracks or cavities between stones, though some species prefer to nest in hollow stems or holes in wood left behind by wood-boring insects.
There are only four species of bees in the Melittidae in North America. Most of those species are oil-collecting bees (Macropis species) which have unique morphology that allows them to collect plant oil, and use it to waterproof their nests and mix with the stored pollen.
Now that you have been introduced to the many different groups of native bees we share our gardens with, become a bee advocate by creating habitat for them and educating others!