It's still a busy time for mason bees! We know that much of the northern part of North America is experiencing a late spring with poor conditions for mason bees to fly. Please be patient and know that as soon as the weather is sunny and warm they will get back to work.
Release mason bees now!
Mason bees survive during hibernation by living off their stored fat reserves. About now their tanks are nearly empty. We recommend that you let your mason bees emerge from their cocoons as soon as you can. Mason bees need to emerge to feed, mate, and begin nesting activity. If you find that your bees haven't emerged, we strongly suggest that you rescue them by opening cocoons up with a pair of scissors. See how to do this on our video. Place the emerged bees on a dandelion or similar broad flower with plenty of nectar. They'll fuel up, fly away and thank you!
If you don't want to rescue bees, consider throwing them away. Cocoons can be filled with mono, a parasitic wasp that laid eggs in the larva last summer and the larva lived long enough to spin a cocoon. This wasp emerges around now through June to begin infected new mason bee larvae through the sidewall of tubes. (We have a new Bee Defender product that will trap and eliminate this pest. It will be available in about two weeks.)
Consider candling your mason bee cocoons. Just like with a chicken egg, you can candle a cocoon to see what is inside! This is an alternative to opening cocoons with scissors and it can help you know how many of your cocoons have adult bees inside. Get a bright flashlight and a small piece of cardboard. Cut a small hole in the middle of the cardboard and use it to shield the light. Hold one cocoon at a time over the focused hole of light. This video will show you three examples of what you might see. We weren't able to find a mono-filled cocoon for this video shoot, but if you see a mass of little bodies, throw it away as these are mono wasps.
What if you don't see any bees nesting? First, understand that you might not be able to see the early signs of bees nesting. If you are comfortable they all flew away, consider what happened from the bee's perspective. We believe the absence of clayey-mud is the number one reason for failure. Was the clayey-mud moist and in a hole nearby? If not that, is a neighbor spraying their lawn with chemical treatments? Lastly, and unfortunately, sometimes a beautiful yard might not work for this spring bee. Please understand that there may be other native hole-nesting bees nearby wanting to use different size holes.
How to check for nesting bees: Shine a flashlight at night into the nesting holes, you are looking for heads or rears in the nesting holes.
When to replenish nesting holes: A female mason
bee will cap the end of her nesting hole with an extra thick layer of mud to protect her precious young. She will then move on to a new nesting hole and begin the hard work all over again. If you see about 40% of the nesting holes filled you may want to think about adding more nesting holes. Simply add new loose nesting material on top of the previous ones.
Make big changes at night: Sometimes, to improve nesting success, you need to move the bee house to a warmer or sunnier location, or you need to make space for fresh nesting materials. The best time to make these big changes is at night. In the morning the nesting female bees will reorient themselves to their new location and the new look of their nesting holes. Be careful not to remove what appears to be an empty nesting hole as a female bee might be sleeping deep inside the hole. Try to keep the orientation of the mason bee house about the same.
Pollen loaves smell good: The sweet scent of pollen and nectar are attractive to birds, earwigs, and ants. Our page about pests, chemicals and drilled wood has tips for how to deter and deal with annoying pests.