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Full of Bees? Must be Swarming Time

Q. We're a horticultural society that runs a community garden. We suddenly have lots of wasps in the garden, especially by the edges of our mulched pathways. Can you help with identification? And a way to eliminate them? We do not like to kill bugs but there are children walking in this area and people actively gardening. Thank you so much.

---Anne in Ontario (just west of Toronto)

A. So, I've already revealed in the headline that these are bees and not any kind of wasp. How did I figure out that they weren't yellowjackets? I mean, c'mon: "wasps" in "mulched pathways"? Gotta be yellowjackets, right?

Right kind of nesting site for sure, but wrong time of year. Yellowjacket colonies don't become large enough to be evident until much later in the season—generally mid-July through September. At this time of year, the yellowjacket Queens that overwintered from last season are just starting to build new nests. You'll certainly see a few stray yellowjackets here and there at this time of year, but nowhere near the numbers that invaded Ontario.

Before I opened the photo they sent, I did suspect it might be blue-winged wasps. Like the ground nesting native bees that appear in the Spring, these big wasps can hover by the hundreds over a smallish section of garden—like a whole bunch did a few years back at the Salvation Army Kroc Center garden in North Philly I helped create. It was quite an experience walking through a horde of large hovering insects (so many that they made a little breeze around me), but they were as docile as could be.

Anyway, it's kind of early in the season for them as well. Right now, you're much more likely to see the ground nesting native 'digger' bees we just mentioned. These native pollinators are solitary bees—meaning that each female has her own little nest. But hundreds of them will often nest right next to each other in a smallish section of bare soil or a ratty patch of lawn. We get a LOT of calls about ground nesting bees in the Spring…

…And it's so nice to be able to assure people that they're just harmless pollinators that don't sting and that will soon vanish for the season. They'd be great to have near a community garden, providing pollination early in the season.

And if there hadn't been a photo attached, ground nesting native bees would have been my guess. But the photo, which we'll post with this Question of the Week, instead shows what seems to be a cluster of honeybees 'swarming' over a pathway of woodchips on the ground.

Honeybees? Crawling on the ground? You bet. There's no telling how a 'swarm' will act when it touches down. "Swarm" being a very definitive word here…

I was reminded of this exact terminology by a story that ran the very same week I got the Canadian email. It appeared on the website of WTOP—the news radio station in Washington DC, where, full disclosure, I have been the 'garden reporter' since 1999.

'TOP reported that a woman in Fredericksburg, Virginia called 911 to report 'a swarm of bees three to four feet tall' on her crepe myrtle. Despite initial skepticism, responders did indeed find a true 'swarm' of honeybees three to four feet tall on her crepe myrtle. Swarms occur in the Spring, when a Queen escapes a beehive, some or all of the workers follow her, and she attempts to set up an independent shop nearby.

The swarm in Virginia was captured by a local beekeeper who estimated the size of the colony at around 40,000 bees. He reports that they transferred easily and acclimated well to one of his hives. And even though that story came out after I answered the email, that's exactly what I urged the Ontarians to do—contact a local beekeeper to evaluate and remove the colony, because honeybees do sting, especially if they're swarming on the ground like the ones in the image from Ontario.

In fact, their being on the ground was my biggest concern. The swarm in Virginia had taken over a crepe myrtle branch; and despite the fact that there were 40,000 of them, no one got stung—not the homeowner, the curious neighbors who came by to gawk, or even the beekeeper who moved them. And that's not surprising. Honeybees aren't aggressive. Most stings happen when somebody in bare feet accidentally steps on one. And researchers feel that the members of a swarm are less aggressive in general.

Anyway, the Canadians followed my suggestion and called a beekeeper who advised them to wait a few days to see if the swarm moved on. If the bees stayed, the keeper said she would come back and try to remove them.

I would want to keep them! The ideal situation would be to move them into an on-site beehive and enjoy their pollinating magic. A swarm in the hive is worth two in the mulch!

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