The main problem with this product is the time it takes to work. If one has a flea infestation results are required sooner than 3 days.
This comes in a cylindrical container, which has holes in the top for dusting it on. However, more ended up in our laps than on the birds; the container is disastrous and totally not thought out. We've seen competitive products in squeezy bottles with a tapered neck/nozzle, which would make them much better for getting under a bird's feathers. Once on though, it is probably very effective, though we gave up. I've bought some diatomatious earth which is supposed to do the same job but is not poisonous, being just a fine earth, like talcum. However, we've yet to try it. It comes in a decent squeezy bottle. Sorry, think again!!!