Thank you for your question and pictures. It appears you have a Pine False Webworm which attacks pine trees and small pines such as a mugho and Scotch pine. The larvae, which is what you are seeing, feed on the plant from May into June and can defoliate a plant. Suggested ways to control this webworm would be to manually remove them by placing them into a bucket of water, or use an insecticide. An insecticide should be administered by a professional arborist who will use the proper insecticide for this invasive pest. Here is a link to find an arborist or pest control professional in your area:

https://extension.umn.edu/home-maintenance-and-safety/hiring-pest-control-professional

Here is more information about the Pine False Webworm in these two links:

https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/pine/needlesclumps.html

https://treefluent.com/pine-tree-worms/