Welcome! Unless your birds are indoors all the time, external parasites will turn up sometimes, from the wild birds. I look ath a few of my birds every week or so, at night when they are roosting, with a flashlight. Look at the vent area, back, and neck, under the feathers. ONE bug on one bird is reason to treat all of them!
Permethrin spray concentrate is the easiest, most cost effective product out there, and works very well. Again, at night spray the birds on the roosts, and spray the coop, including walls, roosts, and tiny nooks. It's approved for poultry, and no egg withdrawal. Don't spray the eggs!! I spray under the bedding, including in the nest boxes, when it will have plenty of time to dry out before morning
Spinosad is also effective, and approved, but is very expensive, and so far not needed, because the permethrin works so well.
In the USA, carbaryl is no longer approved, so don't use it. Many products used on pets are NOT appropriate or approved for poultry. Avoid them too!
DE gets lots of good press, but it's ineffective, dangerous for all of us to inhale, and open pit mined. Not a good product for this. Mary
