Ask-a-Dave's-Gardener: Hydrangea disease or bugs?, 1 by PA_Primrose

PA_Primrose wrote:
I have a six year old Hydrangea that up until this year has been healthy. It is from Endless Summer. I'm in zone 6a.

I noticed in the last week or two that it has a blackish brown spot. It starts at the edges.

I'm not sure if it's a bug (I found a small black and green beetle on it today) Or a mildew or fungus. At first I thought fungus but now I'm leaning toward insects since it's not powdery or noticeably mildewy.

Help! Please. What's happening and how can I stop it?