Pawpaw Pests: Scale Insects on Asimina triloba?

I've frequently read that pawpaws have very few if any pests. Often people will only mention one: the zebra swallowtail butterfly, but then in the same breath they'll say that some people plant pawpaws specifically to attract the butterflies. On the Peterson pawpaw page, the list of pests is a bit more extensive: the Pawpaw Peduncle Borer, leaf spot caused by fungus, occasionally slugs, and also of course the Zebra Swallowtail. People say the pawpaw's leaves and bark are too full of toxins to be palatable to most pests.

So yesterday evening I was surprised to be looking at our KSU-Atwood pawpaw tree and find the branches hosting several bumps--they weren't leaf or flower buds, and I picked one off and it was slimy inside, kind of yellowish, but it didn't have a smell. What could it be, I thought? But then I needed to run off to the pinewood derby.

So this morning after our run, NJ and I looked at the pests and spent several minutes removing all we could find from the KSU-Atwood. We also noticed that they were also (in lesser numbers) on the Wells and the Shenandoah. Here are some pictures.

They seemed most common on the outer extremities of the branches. And they often were in clusters.

For perspective, you can see their size compared to a dime.

On their exterior, they had a type of skin.

When we picked them off the tree, the skin was pliable and generally stayed in tact, but the inside, the part in contact with the branch, was slimy. 

Here are some more.

So you can see, this infestation is happening while the tree is still flowering, and while it is beginning to develop fruit.

Close-up of one.

With a dime for perspective.

Some final pics with the collection I picked off the branches.

Searching for more information this morning, I'm finding that these look like "scale insects," which I gather are pests because they eat the sap of the tree and hence sap its strength. And they can cause mold at the places where they been. Here's a document prepared by a Utah State University extension entomologist, which helps me identify these as "brown soft scale."

I've only been able to find a very few mentions of pawpaws hosting scale insects: here, here, and here. So it seems like scale insects on pawpaws isn't a very documented problem.

I'm so surprised!