Under the soffit there is wood rot, this is located at the end of a gutter at the wall/roof junction, No kickout installed. On top of the window frame is a pile of material that looks and feels like sawdust. Is the carpenter ants, or is it saw dust washing out from under the soffits?
Is that Masonite siding? If it is it may be deteriorating due to moisture. Either way it needs to be corrected and ants may be discovered at that time.
Masonite siding is the worst siding on the market. Due to the sawdust accumulation, I’d recommend an invasive inspection of this area. I believe you’ve either got Carpenter Ant activity here or maybe even mice/vermin pushing the sawdust out of the small swelled openings in the soffit. Concealed sawdust will not fall on it’s own. This shingle area also needs kick out flashing installed, then once this eave area is re-built, a sealant will be needed at all transition areas on a periodic basis.
This type of siding was in the BIG class action lawsuit. The soffit is water damaged, there is no KICKOUT at the wall and end of the gutter. Further evaluation is needed in this area.
The siding looks more like OSB smart panel not masonite.
You might check into that before you report it as masonite.They are definately not the same.
As for the saw dust ,could be bugs could be washed out sawdust from when it was built.How new is it?
It looks like insect deposits to me. If it was water-borne, there would be long streaks, not dry piles. Human sawdust is usually fairly coarse, and like David said, does not move by itself. Ants, carpenter bees, or beetles could be behind the end of that gutter.