Blue pine (Pinus wallichiana), a beautiful tree of high hills in Pakistan, well known for its resistance against insect pests fell prey to a very robust 10 cm long ugly looking looper, identified as Biston regalis Moore. The measuring worm (Geometridae Lepidoptera), absolutely unknown before, appeared all of a sudden in blue pine forests of Murree (50 km from Islamabad) and Azad Kashmir and avaged large areas during 1980 killing tens thousands trees of all ages by complete defoliation. Having an annual life cycle the pest hibernates as pupae in the soil, emerging in May/June as adult moths and veraciously devouring blue pine needles from July to October.