Wooly Aphids on a huge Copper Beech

My neighbours are really angry about all the honeydew covering their cars. (I can't blame them!) I've made several calls and no one seems to know what to do. The tree is about 50' tall so I don't want to spray anything toxic but I would like to rid the tree of the aphids for good because they come back every year. I released a bag of ladybugs a few weeks ago but I can't see any difference. Maybe I should release a bag every week.

Any suggestions? I'd prefer to leave this in the hands of a professional and don't mind paying what it's worth but haven't found anyone with any solutions so far.

 

Surf "woolly beech aphid" for additional discussion.

 

Thanks for pointing me in that direction. Useful info. Sounds like we should just wait for a while and they won't be so much of a problem. We are thinking of releasing a whole lot of ladybugs as well. I hope they like wooly aphids as well as the other kind.