Always assume they have worms.If their feet have ever touched dirt, they've been exposed to worms & it's nothing to fool around with. There's no real way to tell except by having a vet do a fecal. I worm & re-worm everyone while they're in quarantine. You can use Safeguard paste or Valbazen, Safeguard's a ton easier to find. A 1/2" ribbon to each bird and repeat 10 days later. Also-there's a 99% chance they've got lice also. It's common like fleas on dogs. You can use 5 drops of Ivomec Eprinex or Frontline (like for dogs) for that and it'll take care of it for months. The people who swear their birds don't have lice, mites or worms are the ones who've either treated them for it or didn't check well enough to see them. DE does *not work to get rid of lice or mites. At most it *may* prevent them but usually not even that. I worked for a vet for a lot of years and I suppose that's why I'm so OCD about the whole debugging/deworming thing.