It’s enough to make you panic: your lawn has erupted in insect mounds. It’s March in north Florida, and the ant piles in your yard have been dormant for months. Are they back? One day you’re looking at these mounds, and dozens of insects are buzzing in a frenzy around them. What stinging horrors are these? Yellow Jackets? Africanized honey bees? No. These are mining bees, an insect so fierce they’re nicknamed tickle bees.
Tickle bees!
Gosh, they’re actually kind of cute.
Mark Tancig has been getting calls about miner bees. Mark is a Horticulture Extension Agent at the UF/IFAS Leon County Extension. People call the extension for information about plants and gardening, and in this case, how to get rid of tickle bees. “We do try to get folks to consider that they’re just going to be there for a little bit,” Mark told me in an interview for our Coast to Canopy podcast. “Because then, the rest of the year, they’re just down in the ground and they’re not around, potentially disturbing us.”
They’re not above ground for long, and they’re not aggressive. They’re an animal that puts us in tune with the seasonality of our area, emerging as they do when certain flowers bloom. North Florida spring happens in stages. Blueberries start to bloom, then yellow jessamine. Next, native cherry, plum, and holly trees fill with flowers as lawns explode in lyreleaf sage and other winter annuals. When mining bees emerge from their mounds, it feels like spring to me, even if it’s not quite March 20 yet.
Spending most of the year below ground as they do, a lot about mining bees is still a mystery to us. Let’s unwrap as much of that mystery as we can.
Who are the mining bees?
Miners are members of the genus Andrena, in the family Andrenidae. For the few weeks I see them every year, I photograph as many as I can in hopes of identifying different species. I upload them to iNaturalist, and the bee experts almost always select genus Andrena – no species.
The two bees above are the only species-level identifications I’ve ever received for mining bees. Most are hard to tell apart from each other.
Many mining bees are specialists, though. If you see them on a specific tree flower, you might be able to narrow down the species. I mostly see mining bees in trees, such as the cherry laurels in the backyard or the hollies at work.
This bee was so into cherry laurel pollen that it tackled a wilted flower after the bloom faded. iNaturalist’s top bee expert identified this as belonging to the subgenus Archiandrena, which contains two species. One of those, Andrena banksi, visits trees in the Prunus genus, so maybe those are the bees I see in my trees.
Mining Bee Nests
This is what gives the bee its name. Let’s start with the part of the nest we see:
One thing to note is that, when we see their nests, there are many individual nests instead of one large nest. Mining bees are solitary nesters. They may make their nests close to one another, but the bees aren’t organized into a social structure like honeybees or yellowjackets. Social bees and wasps have a queen, and different castes of workers. The hive comes first, so they may risk the lives of a few workers to fend off a large, dangerous human. They give their lives to defend the queen and her hive.
A female mining bee, such as the one in the photo above, is a single mother. She digs down a foot or two into the soil, depositing eggs in cells that branch from the main tunnel. Each egg gets its own ball of pollen to eat when they hatch. If she tries to sting a human, she risks not being able to finish filling the nest with pollen for her babies.
Put simply: social bees and wasps are more likely to sting a human, while solitary nesters are much less likely.
If you read our post on bee nesting habitat, you know that most bees are ground-nesters, and need bare patches of soil. Even on open soil, mining bees sometimes try to conceal their nests. I once watched one crawl under a leaf to dig a nest.
In that post on bee nesting habitat, we learned that wood mulch can block bees from being able to dig into the earth. One interviewee did share an alternative, one that covers the ground in our local pinewoods:
A threat to bee nests
I was leaving Native Nurseries a couple weeks ago when I noticed bees flying low to the ground behind my car. I squatted down to look. There were mining bee mounds all over this part of their dirt parking lot. I went to photograph one with my phone, but when I took a closer look, the bee on the nest wasn’t a mining bee at all. iNaturalist said it was a nomad bee.
Nomad bees of the genus Nomada are kleptoparasites. Kleptoparasitic bees enter the nest of another bee, remove a few eggs, and replace them with her own.
Each species specializes in a different bee or group of bees. I usually see fervid nomad bees in my yard; they specialize in sweat bees of the genus Agapostemon, which are common.
The photo above wasn’t clear enough for a specific ID.
When mining bee nests appeared in an area next to WFSU, as they do every March, I found another nomad:
What a menacing scene.
With my work camera, I had much clearer photos to upload to iNaturalist. The pattern recognition software suggested a nomad that specialized in mining bees, but one that wasn’t found near here, and that looked different. The bee experts didn’t identify a species for it, either.
Note that the bee has no pollen sacs. Her offspring will eat pollen collected by mining bees. These bees may seem like the bad guys, but I will point out that we see far fewer of them than we do of their host species. If they removed too many mining bee eggs from nests, they would lose their host.
The Seasonality of Mining Bees
Mining bees emerge when their preferred nectar sources bloom. Researcher don’t really know how they know their flowers are going to bloom. Their nests are so deep beneath the soil, they don’t likely smell the pollen. Perhaps they sense the ground temperature, or the eggs are set to hatch a certain length of time from when they were deposited.
In north Florida, they overwhelmingly prefer the flowers of tree species that bloom in late February and March. I’ve seen the bees as early as late February, and have seen them make nests in early April.
The nesting colony is most active when the bees are making their nests. Here is when I can photograph a lot of them on the ground, as I’ve done the past two years in the space next to WFSU.
After this frenzy, they’re off to collect pollen. If you hang out for a while, you’ll see individual bees return to provision their nests. But the area is nowhere near as active.
Their time above ground is brief compared to bumblebees or sweat bees that we see through multiple seasons. Their seasonality is their competitive advantage. They are among the first pollinators we see, at a time when there isn’t as much nectar as we see during the summer months. They don’t have to compete with multitudes of bees in the warmer months.
This time of year is a time for specialists. Last year, we met the sandhills cellophane bee, which specializes in a blueberry relative known as climbing fetterbush. Frosted elfins are early-flying butterflies that host on sundial lupine, a plant that sprouts early in the year and blooms in April.
These insects are the appetizer in my year of garden-watching. Soon, plants and insects are going to go crazy here in north Florida, but these guys will all be in the ground before long. I enjoy the brief time I get with them, to watch and learn from them a little bit each year.
Keep an eye out for mining bees (and their stalkers, the nomads) these next few weeks, and don’t be afraid.
Pollinators of a North Florida Backyard
WFSU Ecology Producer Rob Diaz de Villegas has extensively photographed insects in his yard and other north Florida locales. The following pages include the most common species you might see in your yard, which is a surprisingly diverse lot, as well as a few rare or specialized forest species.
