fortunately Ive only got a mealy invasion from one vendor and I never did business with them again.
Just a suggestion is to ask what they use for pest control for their plants on the website or in an email if they arent forthcoming with the info online readily.
Whatever they use switch it up. You have to rotate these pest chemicals or you will make them immune to the treatment and it wont do you any good.
Safari seems to be a common choice for wholesale growers but for us hobby growers using Safari can be very expensive.
But indeed Bonide makes some good systemics and if its good for roses its good for orchids.
When you get your infestation under control try some beneficial insects and keep the pesticides down to a minimum use.
But to be honest with you if a vendor sent me plants with mealies he would have gotten the plants right back wrapped up and choked off in a plastic bio hazard bag . I wouldnt have bothered with a quarantine. I know they are hard to see but if you got a few hundred mealies hes got millions.
Sometimes they appreciate a heads up email you sent me mealies and sometimes they dont.
Bottom line for me is I order/buy from the same good people and dont venture out too much looking for that one off plant anymore.
But good luck to you and smach them mealies with a hammer and they dont come back