Storing mason bees cocoons

Hi Margriet – last year I had almost all of my 20 tubes compromised and broken into by some critter/bird, etc.
I did not have any wire mesh on my two houses.  This year I installed mesh on my houses and had 15 tubes mudded by the Mason Bee(s). Another two were mudded up by a Mason bee Wasp which I observed. After a few weeks, the Mason Bee Wasp tubes had Holes in the opening. The Mason Bee tubes were OK all summer.  Recently, I went up to Princeton for a week and prior to going up, the tubes were doing just fine (Sept. 22).   However, upon returning, several of the tubes had been compromised. In spite of the mesh being in place, I am perturbed as to why this is happening. My brother-in-law who lives in Maple Ridge who I gave several cocoons to, says his tubes are all fine to date. Can you shed any light as to why this might be happening. I was waiting till into October to harvest the cocoons and quite disappointed at this event. Thank you Andy.

PS  a note from Andy in the fall.   I did have ¼ inch mesh once, but saw that the bees were having trouble getting through – with all kinds of antics, falling once through the mesh, and then having trouble getting to the tubes which were about 3 inches away. The mesh surrounded the top, sides and bottom. I did switch to ½ inch mesh which made it much easier for the bees to land on the mesh then fly to their respective tubes.  I did consider mice, and did put some warfarin bait for them, but the bait was not touched, and there was no tell-tale signs of any droppings.

Hello Andy,   After spring and nesting is over, developing mason bees are a great source of food for all kinds of critters.  After spring, wire mesh works for rodents but does not prevent scavengers such as tiny beetles from entering and eating tube contents  (wire mesh during flight interferes with the mason bees nesting and decreases occupancy of nests).

After spring flight is completely over:  Store nest in weather proof area like under a roof or in an open carport.  Rotate bee home so that nesting tunnels are facing towards the wall.  Set nests inside a wasp proof bag to stop wasp parasitism.  Dr. Margriet

Hi Margriet – thanks for responding. After harvesting the rest of my tubes and also the tubes of my brother-in-law – my question to you now is: what do we do with 80 plus cocoons? How do we place the cocoons and in what type of container so they can hatch properly during the Spring? I don’t think it’s a good idea to pile them on top of one another in a small container, so it would take quite a large container for 80 odd cocoons. Let me know what you might suggest. Thanks again,  Andy

Cocoon storage after harvest:  For outside storage, store cocoons in a container that is rodent proof.  A wooden box is a suitable container.  Cocoons piled in 2-3 layers is ok and does not seem to harm the bees.   Set out in early spring, before bloom and create 1/4″ exit hole.  For smaller number of cocoons the hatching hut is the perfect rodent proof box for storing and emerging mason bees.  Dr. Margriet

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