The A Bee Cs of Arizona’s Native Bees

Conjure an image of bees in your mind. Do you imagine a fuzzy insect with black and yellow stripes, a honeycomb nest, maybe a queen bee? If so, you’re not alone. But did you know there are over 20,000 species of bees worldwide, and only a few that produce honey?

Of the approximately 5,000 different species of bees in the United States, around 1,300 live in Arizona, meaning Arizona contains the most diversity of bees in the country, and perhaps the world. In the Sonoran Desert region, biologists estimate there to be upwards of 600-700 native species of bees. These native bees are specialists at pollinating our native flora, as they’ve had quite a bit of practice over thousands to millions of years! They’re also underappreciated by the broader public, and surprisingly understudied. The Tucson Bee Collaborative aims to change that.

The Tucson Bee Collaborative, a partnership between the Desert Museum, the University of Arizona Insect Collection, and Pima Community College, aims to discover and describe the incredible biodiversity of these precious pollinators through DNA sequencing, high-resolution imaging, and ecological research. True to its name, it’s a collaborative effort between researchers, artists, photographers, students, and community scientists! The first order of bees-ness is to begin identifying native bees. Desert Museum volunteers have collected, curated, and identified nearly 16,000 bees across the Tucson Basin to genus. A few hundred of these bees have been identified to species through the collaborative efforts of students from Pima Community College and the University of Arizona and a relatively new tool called DNA barcoding.

The species barcodes are published on the Barcode of Life Database. Photo by Glenn Seplak.

But let’s begin with the bee basics. What are bees, anyway? Members of the order Hymenoptera along with wasps, ants, and sawflies, bees are herbivorous insects (except for parasitic bees – more on these baddies later) with a four-stage life cycle, two sets of wings connected by hooks, and specialized features such as a proboscis and body hair for collecting and transporting pollen, nectar, and floral oils from flowering plants back to their nests. Our native bees often do a better job at pollinating our native plants and many food crops than the famous introduced European honeybee, as they have evolved special relationships with specific flowers. Having evolved from meat-eating wasps, the diversification of vegetarian bees co-occurred with the flourishing of flowering plant species around 100 million years ago, so we almost certainly have bees to thank for our annual flower spectacular!

A bee pays a visit to a buckhorn cholla cactus flower. Photo by Glenn Seplak.

So what about that sweet stuff? Yep, honey. Known to some colloquially as “bee vomit,” honey is floral nectar that’s been processed by insects. Ants, wasps, and bees all have certain species that produce honey, such as the Mexican honey wasp and the honeypot ant. Only a few species of bees produce enough honey to be harvested by humans, and only two, Apis mellifera (European honeybee) and Apis cerana, have been domesticated and put to use pollinating commercial crops on an industrial scale—and producing the massive quantities of honey that line our grocery store shelves and peanut butter sandwiches.

The honeypot ant has specialized workers that serve as living food storage (as opposed to honeycombs, which are external structures) for other ants. They are gorged with food to the point that their abdomens swell with honey, which can be regurgitated and eaten by other worker ants when food is scarce. Photo by D.E. Hurlbert via the Smithsonian.

There are some crucial differences between the honeybee and our native bees. First off, honeybees build honeycomb hives, make lots of honey, and live in highly social colonies led by a queen bee. The majority of our native bees are solitary, and nest in the ground or in above-ground cavities, such as in holes created by beetles or in stems and twigs. Exceptions include native bumble bees which are highly social ground-nesters, and “stingless bees” living in Sonora, Mexico and further south such as Melipona bees that make the highly-prized Melipona honey1. Second, while honeybees can sting, and Africanized honeybees can be aggressive if disturbed, our native bees are generally harmless (all female bees have stingers, but the vast majority don’t use them) . Finally, our native bees come in a huge variety of sizes, shapes, and colors, from massive black carpenter bees to tiny, shiny green sweat bees!

Sweat bee in a barrel cactus flower. Photo by Glenn Seplak.

Now, let’s meet some of our Sonoran Desert underdogs, er, underbees?

Carpenter bees: Recognizable by their size which is exceeded only by queen bumble bees, these bees are large, mostly black, and can be found nesting in dead fruiting stalks of agave, sotol, and yucca as well as sycamore and poplar (depending on species). Their habit of nesting into wood gives them their name. These bees will sometimes steal nectar by cutting the base of the flower, forgoing pollination. How rude!

Carpenter bee. Photo by Phil Brown.

Leafcutter, resin, and mason bees (Megachilidae): These bees make up about 10% of Arizona’s native bee species. Many female leafcutters cut elliptical pieces of leaves and carry these back to their nests, most often in tunnels of dead trees left over by beetles, to protect their brood cells and maintain a constant humidity. Others build their brood cells from mud or clay and still others from plant resins from brittlebush and creosotebush.

Cactus bee (Diadasia rinconis): This species pollinates prickly pear, cholla, and saguaro cacti, among others. Like some of our other native bees, cactus bees can be found nesting with other solitary bees in aggregate nesting sites.

The Flying Saucer torch cactus is a great place for a bee to romp n roll!

Sonoran bumblebee: Like honeybees, bumble bees are social and their colonies include a queen and a worker caste. However, they don’t build hives, preferring instead to nest underground in rodent burrows, mouse nests, or abandoned human objects and sheds. Search for them at thistle flowers.

Cuckoo bee: Like cuckoo birds, these parasitic bees will lay their eggs in the nests of other bees. Because they don’t have to do the work of feeding their young, they largely lack the hairiness of other bees which helps to transport pollen back to the nest. Cuckoo bees do visit flowers and drink nectar, which provides them with the energy needed for flight.

Sweat bees: These tiny bees are ground-nesters that visit a wide variety of plants, and will sometimes visit sweaty humans as they are attracted to salts, hence their name. Occasionally someone is stung when one gets smooshed while sitting on a sweaty arm or leg, but fortunately their stings aren’t painful.

Longhorn bee. Photo by Phil Brown.

Digger bees: So named because they dig nests underground, some common Sonoran Desert bees in this category are squash and gourd bees, specialist pollinators of plants in the Cucumber family. Other digger bees include Centris bees, which commonly visit palo verde flowers and harvest floral oils as food for their young.

Now that you know a little more about the desert’s colorful spectrum of bees, how can you support these essential pollinators?

Notes:

1 In the “Acid” episode of the mini-series Salt Fat Acid Heat, Samrin Nosrat visits Tixcacaltuyu, Mexico to taste and learn about melipona honey. Give it a watch if you’re curious!

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