Linda...if you already have a sand area for dust bathing, it didn't work.
(IMO)
If you aren't comfy handling your birds to check them closely for bugs then why bother trying to "fix" them?
You should go out at night with a flash light and check them when they are roosting.
If you can't...do NOT rely on anything but what is proven to work to kill bugs.
https://www.tractorsupply.com/tsc/product/control-solutions-permethrin-10-1-pt?cm_vc=-10005
(IMO)
If you aren't comfy handling your birds to check them closely for bugs then why bother trying to "fix" them?
You should go out at night with a flash light and check them when they are roosting.
If you can't...do NOT rely on anything but what is proven to work to kill bugs.
https://www.tractorsupply.com/tsc/product/control-solutions-permethrin-10-1-pt?cm_vc=-10005