What is brown looper caterpillar?

The brown looper caterpillar, also known as the common pug, is a moth species of the family Geometridae. It is found in Europe, Asia, and North America, and is known for its distinctive looping movement when it walks. The caterpillar is about 1 inch long, with a brown or greenish-brown body and white stripes along its sides. It feeds on various trees and shrubs, including oak, birch, and hawthorn. The brown looper caterpillar is considered a pest in some areas, as it can defoliate plants and cause damage to crops. However, it is also an important food source for birds and other animals.