Hello, this is my first post although I have been reading for a couple of years now. In an effort to stop the paper wasps, I built a screen house over an 5 x 8 patch of tropical milkweed plants and brought in cats from other patches attempting to raise and release as many butterflies as I could this season. To my great dismay, many turned out to be infected by Tachinid flies. I still have quite a few cats outside and am trying to bring in to a terrarium only the healthiest looking ones to pupate. Looking at the cats, I think that I am spotting wounds on the backs of some ( is this possibly a correct method? ) and generally bringing in only the fattest and best looking of the last big hatch. I also under-estimated how many plants it would take to feed the cats, as the fall migration here was much larger than I expected. So, how do I prevent Tachinid fly infestation and gauge how many cats per plant to allow for. I have a small green house that I over-winter tropical milkweed in. Any other advice for attempting to raise and release monarchs here in north Alabama would be greatly appreciated.