I don't know where you live but if you are in zone 10 Florida, I believe ants will be a major problem. I've seen people in southern Florida go to great lengths to protect their monarchs from ants.

I'm in Southern California.

Other than promoting aphids, what do the ants do to the cats or plants? Do you think a regular window screen would keep them out?

Ants will run off with eggs and caterpillars.

I'm not aware of any real aggressive ants in southern Cal so whatever screening material you use should work out. There are predators that can get through most screening material but they are rarely numerous enough to worry about.

Good luck with the project.

KC

DH is working hard to get it done asap - it's going to be GREAT! I'll post a pic or 2 when it is done.

I've not seen any Monarch's yet, but my tropical milkweed is just starting to bloom, so that should get their attention.

It's a race to see which happens first - eggs or rearing house finished! :-)