Bumblebees recently made a nest by entering through a downspout that passes between a small retaining wall into the dirt. I plugged the opening two days ago and bees still swarm trying to get in. This is right next to a door that goes into my home and yes they get trapped in the house. How long will they continue this pattern before they move on? Hopefully they won’t drill in the flower bed dirt down to where the nest is.
FYI, it is very likely they will create a new entry way to access their home. Plugging the entrance or exit hole should never be the choice of control for any pest; in most cases it will only create a bigger problem. Remember, knowing their route of entry is an advantage you squander when you plug it up. At this point I suggest you leave it be and let them create their “new” entry way. Once they do, you should treat one of two ways.
The first way would be with the DELTAMETHRIN DUST listed in our BUMBLEBEE CONTROL ARTICLE. Simply apply it to their entry hole and you’ll quickly get control. DIATOMACEOUS EARTH can also be used and regardless of which you choose, a CRUSADER HAND DUSTER should be employed to get the dust properly distributed. If you are unsure where this hole has been recreated, dusting the ground in a large area should do the job too. They’ll pick up the dust as they move through the dirt and eventually this will kill them all. The main advantage of the Deltamethrin Dust over the DE dust is that it would last much longer once applied. The DE Dust is organic and won’t be a hazard to people, pets or the flowerbed. However, you’ll probably have to apply it 2-3 times unless you’re able to get it directly in their entrance hole. So in summary, the DE Dust will take a few days longer to work and probably require an extra treatment or two.
The second way to treat the nest would be with some ESFENVALERATE. By soaking a large section of soil you should be able to penetrate with 2-3 gallons deep enough to get to their nest without knowing exactly where it lies. If you prefer to use something organic, go with the MULTI PURPOSE INSECT KILLER. This product works on any insect and will be safe for the garden area too as a certified for “organic gardening”.