Your adult bees in the cocoons need to hibernate until spring. Consider a fat bear and skinny bear going into their cave for hibernation. As their metabolism slows, they are surviving on their stored fats to make it through the winter. Which will survive a long winter best?
Your mason bees are no different. An insect’s metabolism slows down when they are cooler and they absorb less fat. If they are adult bees now, they have begun to absorb their fat. Placing them into a refrigerated environment sooner has them surviving better.
A recent 2010 science study completed by the ARS/Bee Lab confirms that blue orchard bees kept at a constant 40°F (4° C) temperature vs. a sporadic winter temperature have better survival rates and have more energy when they emerge in the spring. Mason bees survive outside fine. However, there will be a larger portion that may not survive due to the fluctuating temperatures.
Refrigerator option:
- In early October, place your cocoons and unopened tubes in a refrigerator with temperatures around 38-40°F degrees. Humidity is needed at about 50-70%.
A small bit of oxygen is also important. (Don’t close the lid on a Tupperware container without adding holes.) - Modern frost-free refrigerators are very dry inside. Most have a moisture content of about 20-30% which is fine for a few weeks, but will dehydrate your cocoons unless kept in your crisper drawer (where there are moist things) or in a mason bee humidity chamber that keeps the humidity around 60-75% which Crown Bees has for sale ($5).
- If stored in a garage refrigerator with fruits that ripen (what fruits/vegetables?), consider that ethylene gas is created which can kill mason bees. Open the refrigerator door occasionally.
- This option allows you to determine when you want your cocoons released in the spring.
- Monthly, it couldn’t hurt to check the cocoon’s condition. Is there adequate water? Do you have mold growing on the surface of the cocoons? If so, this mold has transferred from another source within your refrigerator. It really can’t harm your hibernating bees if it’s just a mild case. Wash the cocoons with 1 tablespoon of bleach to about a cup of cold water for 30 seconds to a minute. Rinse the cocoons in cold water and dry them off with a paper towel before placing them back within the humidity chamber.
Natural outside option:
- Store your cocoons and unopened tubes in an unheated garage or shed where rodents can’t eat them. Plastic tubs will suffice. Ensure that there are a few small holes for air to enter.
- A problem with this option is that when you have a brief warm period, your bees may begin to emerge prematurely.
A little of both?
- Keep your mason bees outside until early Spring. At this point, place them in your refrigerator.
- This allows you to determine when to release your cocoons vs. relying on a sporadic spring. A hibernating bee can survive 6-7 months. Thus, you should be able to hibernate your mason bees through April. If you keep the cocoons in hibernation into May, you will see less survival.
Your website is WONDERFUL! THANK YOU SO MUCH…..
in the section ‘Storing yur cocoons for Hibernation’, you say to put the UNOPENED tubes int the fridge in Oct.
weren’t we supposed to open and clean them in sept/oct?
So, it’s my 1st time…..i attached straws to a friends very active nest last spring, and have about 50 straws w/ some of ‘something’ in them…..I went and got them in probly november, put in my barn all winter, and into the fridge at 40 degrees and 60% humidity …..put in the fridge 2+weeks ago.
yesterday I opened a few….yuck, some of everything, mites, fras, some cocoons, most not full, but most had something…..I was afraid to totally open them all up so close to hatching, so
I washed the tubes/straws, removing junk and any mites (a spider and 2 wasps) off at least the OUTside of tubes and put back in the fridge.
what do i do? i’m afraid the mite situaltion is bad and don’t want to keep that going, making it worse here at home, with these bees, in a place I want to just start managing them here at home……
do i toss em all and start w/ new cocoons from friends? do i open them and clean as possible this late?
HELP!
it’s raining and cold, want to just release 5-10 tubes per week ideally, starting this or next week.
thank you…..becky on Guemes Island (anacortes).
Hi Becky,
Pollen mites are an unfortunate pest that can’t be stopped as they build up during spring nest rearing, but can be controlled prior to release. Although yucky… I would open each tube up and rescue the healthy cocoons now rather than have the bees forced to march through the mites. They’ll wind up carrying mites on their backs because they won’t be able to get rid of them. This affects their ability to fly well.
There is no reason to start over again as you have the cocoons in your hands. These are valuable insects that you’ll have to muscle through the pests to rescue! Your bees will thank you.
Hi dave-
thanks SO much for the support and info…
and muscle thru I did. I had to skip lunch that day……fascinated and horrified, using the 10x handlens to look at everything……i was DIS>>GUSTED>>>>yuck!
but i did it….much loss but a few keepers.
that taught me a huge lesson about maintaining my little nesters.
~Becky
We just took our Crown Bees out of ourgarage refrigerator where we kept them in an empty crisper drawer. I added water as specified on the plastic box we bought for the purpose during the time they were in the refrigerator. We have just taken them out and put them in their outside house. My husband opened the boxes and found mold on the caccoons–that sounds like trouble to me–do we have a problem? We bought two of your Crown Bees boxes and put them in the contained sold for such a purpose.
Mold grows on surfaces that are moist and full of live things. I wrote a bee-mail about this mid December. …and I’ll write a note in this post after this comment! Mold spores typically are airborne transmitters. Air flow in a refrigerator can pull mold from cheese, old whatevers, and spread it to other organisms nearby. It’s not that the cocoons had mold to start with, rather they received it from someplace else.
The mold really isn’t harmful to our hibernating bees. When in doubt, it’s very easy to wash the cocoons in a cold water bath with a bit of bleach that will kill the mold. A tablespoon of bleach to a cup of water is fine. Rinse the cocoons in this bath and then rinse them off with more water. Dry them off with a paper towel and put them back in until you’re ready to put them out. I might check on the cocoons monthly.
Thanks for the quick reply. I didn’t think the Bees started out with mold–I was afraid I had done something wrong in taking care of them. Our garage refer is really kept very clean and they were in a crisper drawer by themselves. I will be even more careful in the future now that I know what could possibly cause the mold. I clean everything else with bleach, why not my Mason Bees.
Thanks again for your response. I am looking forward to the little bees flying all over our fruit trees and doing their good work.