frames and foundation cost up 40%

[Wingy]

if they want drone cells they make drone cells. When they no longer need them they fill them in a bit and make them into worker cells

 

[user 20917]

Make your own foundation. I have been doing that for almost 30 years.

 

[user 819]

Nowadays I let my bees build the foundation/wax, though I do have some in the cupboard still all wrapped up.

 

[polymath]

I don't attempt to control drone cells ... if they want drones they will build drone cells ... usually up to about 20% of the brood in my foundationless frames are drones. Perhaps that's what your bees wanted and you gave them the opportunity ?

This aligns with what Tom Seeley finds in the wild i.e. circa 20%.