Actually roaches are more commonly a source of tapeworm. Roundworm is really easily picked up from the soil, and the Florida sandy soil and climate makes it a parasite breeding ground. I have to worm regularly, every 3 to 4 months for round worm in my flock. It's nearly impossible to completely eradicate it from your environment once it's there. Rotating pens/pastures, keeping droppings cleaned up as well as possible, keeping feeders and waterers clean, and monitoring and treating as necessary are your best bets to minimize it, and keep healthy birds. Keeping grass cut short, so the sun can hit the soil can help also. There are a lot of articles available on how to help reduce parasite loads, but getting rid of then totally is not really possible. I rotate Valbazen and Safeguard for regular worming, they both work very well at the proper doses, and rotating helps prevent breeding resistant parasites. If you ever have to treat for tapeworm (I've got all the same bugs and roaches/palmetto bugs are just part of Florida) then praziquantel is the best for that. I've not had tapes in my flock despite all the roaches.