Sawflies are not true caterpillars, but do resemble them. They are voracious feeders, and in high numbers can devour a plant in days. European pine sawfly is commonly found on Mugo pine, but can also be found on other hard pines. Azalea sawfly is another common sawfly pest.
A foliar treatment is most effective at controlling sawflies, and timing is critical as they cause great damage in their short life span.