Sweat Bees: Friend or Foe in the Garden?
Have you ever been out working in your garden and suddenly discover you have a tiny bee sitting happily on your arm? These little creatures are sweat bees, and they likely think your sweat is delicious.
|Common Name(s)||Alkali bee, sand sweat bee, sharp-collared furrow bee, and many others|
|Scientific Name(s)||Nomia melanderi, Lasioglossum vierecki, Dialictus vierecki, Halictus vierecki, and hundreds of others.|
|Plants Affected||None harmed, but most ornamental and many edible flowers are pollinated|
|Common Remedies||Scented soaps or essential oils to mask the smell of human sweat. Avoid nests if possible so they can continue to pollinate. If nests are inconvenient, contact professional to remove them, or place water or plant lures to draw the bees in an uninhabited direction.|
What Are Sweat Bees?
The name “sweat bee” elicits an obvious response: they’re bees who are attracted to us by our sweat. And it’s at least partially accurate. But there’s a lot more to them than that!
Sweat bees are tiny bees who are members of the Halictidae family, some of which are parasitic species. Also referred to as ground bees or ground-dwelling bees, these wild bees aren’t honey-producers in the same way as the Apis family of bees are. However, sweat bees are still amazing pollinators!
What does a sweat bee look like? In short, it varies. So let’s go over some of the different species and talk about these less-familiar bee types.
Types Of Sweat Bees
There are many species, with approximately 4300 subspecies in the Halictidae family worldwide, but different regions will have different subspecies of sweat bees. There are more than a thousand species in the USA alone.
In describing halictid bees or sweat bees, there are three parts to their bodies: the head, the thorax, and the metasoma or abdomen. The head is obvious; the thorax is the body, and the metasoma is the bee’s bulbous rear end. Often these will be differently-colored.
With so many species, it’s not possible way to cover them all in one burst. Here’s a few of the most commonly-recognized varieties of sweat bees.
Nomia melanderi, ‘Alkali Bee’
Found throughout the western US, the alkali bee species makes its home in semi-arid or arid desert regions.
Male and female alkali bees look very similar, almost like a cross between a wasp and a bee. Both have distinctly fuzzy thoraxes, with a yellow and brown striped metasoma. Males have distinct antennae which look almost like a pair of horns.
The alkali bee has learned how to open alfalfa flowers by putting pressure on the base of the flower, ensuring they have first selection of new pollen. Their name originates from their habit of nesting in alkaline, salty soils.
Lasioglossum vierecki, ‘Sand Sweat Bee’, ‘Dialictus vierecki’, ‘Halictus vierecki’
Found in the easternmost third of the US, sand sweat bees are often mistaken for being some form of wild honeybee.
Both the males and females have an orange-yellow tone to their metasoma with bright, golden-yellow hair. Visually these are quite hairy sweat bees, almost fluffy in appearance.
Females are brighter in coloration, with a green-tinted head and thorax. Males tend to be more of a brassy-green coloration.
The sand sweat bee gets its name because it nests in the sand, but also because it prefers plants which dwell in sandy environments. These sweat bees are solitary bees by nature, and the female will raise her own young in a separate nest.
Lasioglossum malachurum, ‘Sharp-Collared Furrow Bee’
Found throughout much of continental Europe and parts of North Africa, the sharp-collared furrow bee is a common palearctic species of sweat bees.
Both males and females of this species tend to be a reasonably uniform dark brown hue with bands of a pale tan color. Other than their coloring, they look quite similar to common honeybees.
These ground-dwelling sweat bees will dig deep holes in hard-packed soil to live within. Due to the difficulty of burrowing their nest, generations of these halictid bees may squabble over previously-dug sites. They are eusocial and have queens and workers like honeybees, albeit not as distinctly separate.
Lasioglossum zephyrum, ‘Common Eastern Sweat Bee’, ‘Dialictus zephrum’
From the eastern coast of the US and Canada all the way to Texas, the common eastern sweat bee can be found during warm-weather conditions.
Females are a brass-green coloration with a reddish tone to their underside. Males are similar, except they are more of a bright or neon green bee with a more brilliant red hue on their underside, and tend to be slightly larger than the females.
These sweat bees are extremely productive pollinators, with an extensive range of plants they favor. They are eusocial, with a queen producing young and workers helping to provide food and shelter for the young.
Agapostemon splendens, ‘Brown-Winged Striped-Sweat Bee’
From North Dakota to Texas and all the way to the eastern coast, the brown-winged striped-sweat bee dwells. It is the largest population of sweat bees in the eastern half of the US. There have been sightings of this bee species in southern Canada and northeastern Mexico as well.
Males are a blue-green iridescent hue with a golden and black-striped metasoma, and tend to be slightly metallic in appearance. The females are iridescent, slightly-metallic blue-green that tinges to purple along the sides, and have dark banding across their blue-green metasoma.
Brown-winged striped-sweat bees are common pollinators of a wide number of ornamental plants, but may also pollinate some edibles.
Agapostemon sericeus, ‘Silky Striped-Sweat Bee’, ‘Agapostemon pulchra’, ‘Agapostemon sitlcatulits’
These iridescent sweat bees are found on the eastern side of North America. They range from Manitoba, Canada south to Florida on a north-south axis, and from Nebraska to Massachusetts on the east-west axis.
The females of this species of sweat bees are fully iridescent in shades of blue and green with the exception of amber-colored legs and wings. Males have wide black bands on a goldenrod-yellow metasoma.
Silky striped-sweat bees like a wide range of pollens from both ornamental and edible plants, and are considered a consistent pollinator on the eastern half of the United States.
Agapostemon melliventris, ‘Honey-Tailed Striped-Sweat Bee’, ‘Agapostemon fasciatus’, ‘Halictus plurifasciatus’
Found throughout the southwestern United States and into northern Mexico most, the honey-tailed striped-sweat bee has been found as far away as Kansas or Montana. It’s a very common pollinator for alfalfa crops throughout California.
Males of this species have metallic green heads and thoraxes, and a yellow metasoma with thin black bands. Females have metallic green heads and thoraxes, and a honey-colored metasoma with white hairy bands.
In the alfalfa fields of California, it’s been reported that honey-tailed striped-sweat bees will nest in the soil beneath the cultivation level of fields, close by for easy access. These sweat bees are not limited solely to alfalfa as a host crop, but seem to be partial to it.
Agapostemon angelicus, ‘Angeles Striped-Sweat Bee’
The Angeles striped-sweat bee lives in the western and central US, with a range extending up into parts of western Canada and down into Mexico. However, these sweat bees are most common in and around the desert southwestern region of the US.
The female is a metallic green bee across its entire body. Males are green across their head and thorax, but the metasoma is bright yellow and black banded.
In the evening, these sweat bees can be found sleeping on larger flowers. Females prefer to be solitary insects, and males may cluster together with multiple sharing a single large flower blossom.
Agapostemon coloradinus, ‘Colorado Striped-Sweat Bee’
Primarily found in the Rocky Mountains and the nearby plains of Colorado and Utah, this sweat bee may also be found in portions of Idaho and Oregon, albeit rarely.
The male is a bee with green head and thorax which can also appear blue. Its metasoma is banded with pale yellow and black. Females are blue or green bees with a black metasoma that’s banded with short, whitish hairs.
Very little is known of the nesting habits of this particular species of sweat bees, likely because of their limited range.
Life Cycle Of Sweat Bees
Sweat bees are still being studied, and different species of halictid bees have different life cycles. However, two very distinct variations are observed.
A female solitary sweat bee will find a suitable place to dig her nest, and spend days preparing it. She will then work frantically to gather pollen and nectar to create a pollen ball which is placed where her eggs are laid. The young larvae will feed on the pollen ball until they mature.
Once the young have reached adulthood, they also go out into the world. There can be many lifecycles during the space of a year. Young females are trained as workers, but may dig their own nest or claim one that’s no longer in use.
Before winter hibernation, females will mate again, ensuring they are ready to have young when they wake.
However, some species of sweat bees are eusocial, meaning that a few nest in a sort of colony. Sweat bees will have several breeding queens, and may share the entrance tunnel to their nest with other females. Individual females will dig offshoot chambers for their young.
Some species of sweat bees in a eusocial colony may act as workers, and carry pollen for females. This job is primarily done by the males and any females who are not currently breeding. As a female reaches breeding age, she may stop being a worker to dig her own chamber and have young.
While there is some variation between species, most sweat bees tend to nest either in burrows dug in the ground, or burrows dug into rotting wood.
In some cases, the initial tunnel off the burrow may be shared by multiple queens and workers, but individual queens will dig side chambers off the main chute. Other species have a single, deep hole with a chamber at the end, and guard it from other sweat bees.
Sweat bees which live in wood typically choose partially-rotting wood as it’s easier to dig burrows into, but they are similar to those in the soil in terms of their construction.
Often sweat bees’ nests will be placed in close proximity to a source of pollen and nectar, occasionally close to a water source.
What Do They Eat?
Like most bee species, sweat bees consume and carry pollen and nectar. The larvae are often laid in sealed chambers filled with nectar and pollen from which they emerge as adults. They also seek out sources of salt, although in lesser quantities than pollen and nectar.
Why Are They Called Sweat Bees?
Like us, sweat bees are reliant on a certain amount of sodium to maintain good health. Unfortunately, there is not a lot of salt to be found in flowers or pollen. So these little bees have had to evolve a method to find the life-sustaining salt that they need.
Over time, they have adapted to develop a long, slender tongue which enables them to lick sweat off of humans. This satisfies their salt requirements. They also may find sodium through saltwater along beaches or in dew infused with salt spray, but salty sweat’s everywhere!
Are They Pests Or Good Garden Guests?
Often, we think of bees in general as being great in the garden, and sweat bees are no different. Just like honeybees, these wild bees are fantastic pollinators and will happily move from flower to flower in your yard pollinating stone fruits, ornamentals, and veggies alike.
As a general rule, they do not tend to sting unless they’re directly threatened. Even those that land on you to have a taste of perspiration are disinclined to sting — all they want is a drink! But they can be quite persistent, which can be intimidating if you’re unready.
If their nest is left alone, they’re a wonderful addition to your garden landscape. The only difficulty arises if the nest has been made in an area that is heavily trafficked, such as directly in your garden beds or near where children or pets play.
While they are less defensive about their burrows than honeybees are of their hives, you still may be at risk if you are right next to it. Things that can trigger defense mechanisms include vibrations at the nest site and dark shadows over the nest entry.
Blocking a sweat bee from returning to its burrow can also cause the tiny bee to become defensive. Never block the way for a sweat bee to go home!
Eusocial bees can become a problem over time as the colony grows. If you like to work outdoors in hot weather, you may find yourself swarmed by bees who are attracted to the salt you’re producing in your sweat. Therefore a sweat bee infestation may be a problem.
In addition, they often migrate back to where they were born to have young. As you may imagine, what was once a solitary bee might become a much bigger issue over time.
Controlling Sweat Bees In Your Garden
For most people, sweat bees will never be present in a large enough quantity to cause a sweat bee infestation. The occasional bee buzzing you for a human sweat sample might be an annoyance, but if you don’t swat at it, it’ll drink and go away. Most of the time you won’t need to control sweat bees. But what if you’ve got a sizeable colony in your yard?
The simplest option may be to call a beekeeping expert. Halictid colonies are not the same as apis hives, but most professionals know how to deal with them. They may remove them entirely or block the hive entrances so that bees cannot enter or exit.
It’s extremely rare that you would need to use a pesticide to combat them, and in fact, I recommend avoiding it as much as possible. Like honeybees, these are essential to our gardens, and killing them off can endanger other bees.
Instead, it’s best to make your garden a great place to visit, but not to live. That way, you can have the best of both worlds.
Since some varieties, like the alkali bee, prefer alkaline soil, ensuring that you have neutral pH soil can fix the problem before it starts. In addition, softer soils with lots of organic material tend to deter them, as they prefer harder soil that they can burrow into.
If they are becoming pests during the summer months around your pool, they’re likely just searching for water. If they have an alternate water source, they’re more likely to go to the quieter point than to risk getting wet where your kids are playing. Giving them a source of hydration means you won’t skimp on pollen-laden stone fruits.
Place a bird bath or water feature somewhere away from your pool to encourage the bees to go to that location. Even a bowl of water will work to keep the bees away from you.
Interestingly enough, they can be deterred from landing on you by a number of essential oils. These block the smell of sweat, so the bees don’t find it. Citronella, peppermint, cedar, orange, or nearly any pungent-smelling oil will work. Even peppermint-scented soap works!
Finally, if you know where the nest is located, you can always place bowls of saltwater nearby so that the bees go there for their salt fix rather than trying to land on you. The bees are less likely to risk themselves by approaching humans that way.
If you find that they’re still consistently a problem and feel as though you need to reduce the population, I still don’t recommend pesticides. Instead, make a soap spray. Use 1/4 cup of dish soap to a cup of water, and mix well. Place it into a spray bottle.
This soap spray will leave a residue on the bees that weighs them down. They will find it very difficult to fly after being sprayed, perhaps completely impossible. Also, you will be killing your pollinators by doing this. However, it is not risky to pets or humans.
Frequently Asked Questions
Q: Is their sting dangerous or painful?
A: It depends on the type of halictid, and whether you have any sensitivity to bee stings. These tiny bees have an equally-tiny stinger, and most people report it’s no more than a minor nuisance at best. Many people don’t even notice it!
However, the stinger may be left in your skin afterwards and can continue to be a nuisance. If that’s the case, carefully remove it with a pair of tweezers, the same way you’d remove a sliver.
If you do have bee allergies, it’s important to treat this as if it were any other bee and follow your doctor’s recommendations. Even if you’re not sensitive to bee stings, if you have reddening or swelling of the skin, it’s good to see a doctor.
Q: Do they die when they sting you?
A: Like other bees, the stinger of a sweat bee has a tiny hook or barb on the end. While they can sting many other animals and other bees more than once, the barb will get caught in thick human skin.
Unfortunately, most of the time, that means that it literally tears off the stinger and part of the bee’s abdomen when the bee tries to escape. So like honeybees, they usually do die when they sting humans. Thankfully, they don’t sting us often!
Q: Do they swarm?
A: Not in the same way that honeybees do. Honeybees live in a very regimented hive structure, and there many be hundreds of bees. When new queens form, part of the hive will follow the new queen in a swarm to a new location.
By contrast, most sweat bees are solitary bees, or at best eusocial bees. They’re not inclined to move as a swarm of bee families anywhere, being considerably more free-spirited. This means it’s highly unlikely that you’ll see a large number of them.
If you do see a large number of them, it’s very likely that you’re close to a colony site, and that multiple bees are nesting nearby. Try to avoid disturbing the nest if at all possible, and you shouldn’t have any problems other than a stray bee stopping by for a drink of liquid salt!