[btilly]

I've been to https://www.butchartgardens.com/. It is admittedly a highly artificial example, but it is an extremely pretty reclaimed coal mine that is reasonably large, and with good plant diversity. They don't use herbicides or pesticides, but instead rely on released insects to protect the plants. (Unfortunately they have not found an alternative to fungicides to protect the roses.) This suggests at least some insect diversity.