Bark beetles?

Bark beetles (likely Southern Pine Beetle or Ips beetles given the pine needle litter) bore under the bark and carve winding tunnels that cut off the tree's nutrient flow. The orange frass is very characteristic of their activity.

Ants (carpenter ants especially) do excavate pine wood, but they prefer already-dead or very wet/rotted wood, and their damage looks more like clean, smooth galleries. Ants are often a secondary visitor after beetles have done the initial damage.

What to do:

• Check if the tree has a full crown of green needles or if it's browning/thinning — that will tell you how far along the decline is
• If bark beetles are confirmed and the tree is significantly infested, it typically cannot be saved
• Removal may be necessary, especially if it's near structures, as beetle-killed trees become hazardous fairly quickly