How high does the "bug layer" extend?
In 1961 study a plane flew 116,684 miles sampling the air, catching whatever was up there, and managed to capture a single termite at 19,000 feet. This is the highest ever observed.

You just never get above the "bug layer" in a smaller aircraft (Cessna 172 limit is 15,000 feet). Likely this is not a proper naming.