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Extension > Yard and Garden News > Ground nesting BEES Colletes Part I: Building a nest

Thursday, October 2, 2014

Ground nesting BEES Colletes Part I: Building a nest

Karl Foord, Extension Educator - Horticulture

One of our early emerging vernal native bees is in the genus Colletes. These bees are commonly called plasterer bees, cellophane, or polyester bees. This is because the bee builds an underground nest and then paints/applies/lines her nest with a cellophane-like plastic material secreted from an abdominal gland. The bee applies this material with her two-lobe tipped tongue. This secretion helps protect the developing bees from fungal disease and acts as a waterproof barrier. It is so effective that ground-nesting species can occupy areas prone to flooding.

I photographed a Colletes bee digging a nest. The nest took several hours to dig which I videoed and then cut out much of the inactivity to create a 5 minute video.

One of today's landscaping rules-of-thumb is to cover bare soil with mulch to both prevent erosion and discourage weed encroachment. This makes sense, however should we reconsider this practice in light of our need to provide nesting habitat for native bees? Perhaps there are areas in the garden or proximal to the garden which could be left open and undisturbed.

Though not specifically stated open soil areas were considered a sign slovenliness, something not tolerated in my upbringing environment. Somewhat along the line of "There are no dirty or lazy Zimmerman's". Something my maternal grandmother used to say.

The two main threats to most pollinators include habitat loss and pesticide use.

You can create a welcoming environment to ground nesting bees by doing the following:

1. Leave bare patches of ground in your garden or yard to help provide nesting sites. It may look unkempt but it is unkempt with a purpose.

2. Plant a variety of bee friendly nectar and pollen rich native plants. A good place to start is "Plants for Minnesota Bees" by Elaine Evans.



Elaine Evans

Photo 1: Plants for Minnesota Bees (front)





Elaine Evans

Photo 2: Plants for Minnesota Bees (back)

3. I have decided that to the extent possible I would rather watch what is happening in my garden then attempt to kill certain pests with the high likelihood of killing beneficials. My worst garden pest is the four-lined plant bug which attacks my anise hyssop. Given how I feel about anise hyssop (possibly the best bee plant I have encountered) you can imagine how motivated I would be to remove these pests. I have controlled them to my satisfaction by clapping my hands on the leaves where I see the bugs. The leaves tolerate this much more than the four-lined plant bugs. Avoiding the use of synthetic pesticides in your garden and on your lawn is recommended.

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