Why are mason bees not nesting in my bee house?

For first-time mason bee raisers, this is our most common question in the spring. 

First, please be patient. It takes time for the mason bees to emerge from their cocoons and it can take up to two weeks to see mason bee activity at your bee house. Female bees have to find flowers, clay mud, mate, and then they return to nest; and they can also be away from the bee house for up to 30 minutes while gathering pollen, nectar, or mud. Bees also begin building their nest at the very back of the nesting hole where they are hard to see while inside the nest.

Next, please check to see how many bees have emerged from their cocoons. Mason bees use temperature cues to tell them to emerge and they need a minimum of 50F daytime highs to emerge.

Nesting bees leave a few signs of nesting:

You may see a bee sitting in her nesting hole in early morning or at dusk.

You will find a mud-capped end to a nesting hole.

You may see yellow pollen marks on the ends of your nesting holes.

Here are the questions that we ask our customers to help them determine any troubleshooting areas. Unfortunately, sometimes we do everything right and since mason bees are wild creatures, they can decide to nest elsewhere for reasons unknown.

Troubleshooting questions

1. How is the weather? Mason bees begin to emerge when daytime highs are above 50F and they start to fly when daytime highs near 55F. Bees are cold-blooded and poor weather will limit their flying activity. Male bees take shelter on nearby plants and sometimes use the bee house for shelter.
   
2. Is your bee house in a good location? Mason bees like to sunbathe in the morning and this is why we recommend installing your bee house in a morning sun location. If your yard is shady, consider installing your bee house in a spot that gets the most exposure to sun throughout the day, even if this means that the bee house gets afternoon sun. If you need to move your bee house, do it at night so any nesting bees have time to reorient to their new surroundings in the morning.
   
3. Does your yard offer clayey mud? Mason bees won't nest if they can't find clayey mud nearby. See our Making Mud for Mason Bees article for tips.
   
4. Do you have enough open flowers nearby? Each female mason bee can visit up to 2,000 flowers per day - take a look at your open flowers. Winter-blooming heather is a good early blooming plant that has a long-lasting flower in the spring. Young fruit trees may not be enticing to mason bees, consider adding blueberry, raspberry, or strawberry plants near your fruit trees to help feed the bees.
   
5. Are birds or other critters bothering your bee house? A sign that a woodpecker or squirrel was interested in eating your bees is when you find your loose nesting holes strewn on the ground. Install our Bird Guard to the front of your bee house.
   
6. Do you avoid lawn care chemicals? Solitary bees like mason bees are pickier than social bees when it comes to where they live. Solitary bees only fly in a 300-foot radius from their bee house and some lawn chemicals can harm or deter bees from nesting. Avoid chemical applications before and while bees are nesting. Be aware that chemicals applied in your neighbor's yard may drift into yours and deter your bees.