What type of bugs eats foam insulation?

https://www.doityourself.com/stry/how-to-deal-with-insect-problems-in-your-foam-insulation

I cannot tell from picture. are you actually seeing a type of insect or just the wearing holes or something from them?

Either termites or carpenter ants.

You can see in the photo how the eaten areas resemble the same type of "colony" features as a glass hobbyists ant farm looks.

You should contact an exterminator company and they can also replace the foam with an insect repellent foam as well.

If you have an insect problem in your foam insulation, removing them can be difficult. Insects don't eat foam insulation, they tunnel into it. These tunnels lower the insulation properties of the foam insulation. Most foam insulation is coated with borate to prevent insects from infesting it. Removing pests from you home may take a number of months. Removal techniques involve poisons, and may harm small pets or children. In some cases removal of the insulation and starting over from the beginning may be the best alternative.

https://www.envirocarepestcontrol.net/2016/03/12/termites-can-eat-through-foam-insulation/

This will help you out! http://www.contractortalk.com/f4/whats-eating-foam-48176/