Most likely, the critters are woolly beech aphids. Around here, beech and those aphids are a "set."

Power hose as much of the tree as you can, repeating every several days. Or consider hiring a tree service.

Could you describe the insect?

http://www.biopol.nl/UK/MealyBugs.htm good picture of this little vermin

But are you sure that you have mealy bugs and not the wooly beech aphid as Jean suggests? They look quite similiar upon quick inspection, but the latter seems more likely.

Would it be possible for you to send a picture of the ACTUAL critters on YOUR tree?

hope this shows up

Here is a link that might be useful: {{gwi:1155293}}

Well, your picture is a tad small. But the location of the critters tells me they're woolly beech aphids.

Because woolly aphids have a white waxy coating they can be mistaken for mealies.

If you look at your critters with a strong magnifying glass (I prefer a 10X hand lens), you'll see that your critters are aphids, woolly ones.

i agree - after webbing good sites, it looks like what you describe. i went out this a.m. and used the hose underneath, holding leaves to drive them away. does this mean the end of them for now? i can see where insecticides would have no value. i also discovered an emerging bagworm...what an UGLY critter. only one. will keep an eye out now for more. is it possible the walmarts mulch could have carried in the aphids? not looking for blame, only to try to figure out why after all these years my beautiful tree is under attack. and THANK YOU whoever you are.

It would be worth using insecticidal soap on the aphids. Truthfully, you've selected a plant that may be predisposed for such an infestation. You may even have to learn to live with a minor outbreak on an annual basis. Dormant season applications of horticultural oil might help smother eggs, thus decreasing the population the following spring.

I agree with you that those bagworms are ugly. They, too, can be controlled with insecticidal soaps while still young or when not in their protective mobile homes.

Oh, the aphids did not come in your mulch.

mbauer,
I was getting tired of the ordeal of filling up my tank sprayer with soapy water (I use Fels-Naptha), so I decided to just turn the hose on my trees and scrubs (after inspecting), and I did this every day until there wasn't an aphid in sight. My River Birch didn't have any aphids this year and I believe it was because I used a systemic before the leaves came out. Last year the aphids did so much damage to the new leaves before I realized what was happening.)

Around here too...Beech trees and Wooly aphids go hand in hand.

Vera