How to attract bumbles to an artificial nest
If you’ve made or purchased a bumble bee box, you are probably wondering where to put it and how to attract tenants. I’ve scanned dozens of documents looking for the secret formula and learned that location is the most important criterion, followed by nesting material. Moisture control runs a close third. Even so, most bumble bee enthusiasts report an average occupancy rate of about 30 percent.
What follows is a summary of all the suggestions I found. I have a bumble house that I purchased several years ago that I use for show-and-tell, but I’ve never actually set it outside. After one more demonstration later this week, I’m finally going to try it. We get lots of bumbles here of various species, so I’m cautiously optimistic.
I’ll start with location since it is important and comprises many variables:
- According to The Natural History of Bumblebees by Kearns and Thomson, “by far the best site is a south-facing bank.”
- The box should be placed in full or partial shade. If the interior gets too hot, the larvae will cook. If the box will be in the sun part of the day, morning sun is better than afternoon sun.
- The box opening should face the morning sun (east or southeast) even if it is not directly in the sun.
- The box should be sheltered from the wind.
- The entrance should be at ground level.
- Other good nesting areas include:
- Under a hedge
- At the base of a fence
- Alongside a garden shed or wood shed
Bumble bees do not collect nesting materials so they select nest sites that are already outfitted with the materials they need. In nature, they often select rodent burrows, birdhouses, leaf litter, or debris piles. You have a much better chance of attracting bumble bees if they approve of your choice. Possible nesting materials include:
- Dry moss
- Grass clippings
- Shredded paper
- Hamster bedding
- Upholstery cotton or cotton batting (surgical cotton is too fine and may entangle their legs or wings)
By the way, if you have a two-chambered box, the nesting material goes in the inner one.
A bumble bee may set up a nest only to move out if the nest becomes damp or water-logged. To control moisture, place the nest box on a concrete block and provide an over-hanging roof. You can also drill several small drainage holes in the floor of the box. Be sure the nest location is away from sprinklers.
Due to moisture problems, some people prefer to mount the boxes 8-12 inches off the ground, attached to a fence post or building. This above-ground entrance will work for some–but not all–species of bumble bee.
The nest should be placed within a half-mile of early blooming plants, but the closer the better. If you put the box in an area where bumbles are common, you have a better chance of attracting a nesting female.
Secure the box to avoid predation from small mammals such as opossums, raccoons, mice, weasels, voles, moles, and shrews that enjoy a savory meal of bee brood. Ants can also be a problem around bumble bee nests. Bumble bees like a secluded spot, so choose an area away from pets and human traffic.
In many parts of North America the early queens will start house-hunting by mid-February, as soon as the earliest flowers begin to bloom, so it’s not too soon to set out your box.