I don't know. I need to study up on those pesky Mexican long-tongued bats.
I live in the Tucson area too — and had/have this same bat problem.
These migratory nectar bats come here from Mexico to pollinate certain kinds of cacti in the desert. Unfortunately they have discovered hummer feeders, which may be easier (and have more nectar)?
I was told (wildlife expert) that the nectar bats leave "after the second cold snap." That seemed to be true last year. ( The time of their leaving is not related to availability of sugar water in hummer feeders.)
Even though I have fewer hummers in summer than winter, I still have quite a few feeders out all summer .... and have no inclination whatsoever to bring them inside every nite and then take them back out early every morning. Good grief.
Bottom line: Wild Birds Unlimited sent a newsletter last year that featured a nice bat cage — which they make and sell. (Tanque Verde store between Wilmot and Sabino Canyon Rd.) Yay! It works! Hummers can get inside and bats can't. Cost is around $30.00, as I recall.
One cage isn't enough for me, so this year I am going to try to make a couple more, using (upside down) hanging baskets — the steel kind that are used for flowers. Ace Hardware sells them for around $5.00. I may need to wire some screen, hardware cloth, chicken wire or something over the bottom. If this experiment doesn't pan out, I'll probably purchase another cage. Or maybe I could just hang all the feeders on the arms of one feeder pole and wrap chicken wire(field fence?) around the whole thing.
The whole situation is a nuisance. The bats need to stay out in the desert with their cacti.
Bats are "endangered and protected" (federal? state? both?)... Guess you knew that.
Bats carry rabies. A dead rabid one was found in our neighborhood. I had my house sealed by a wildlife company so they can't live here.
Now if someone would just figure out a way to exclude all of these bees! :eek!::eek!: