The Geometridae is a large family of moths with more than 30,000 species. Various species are considered to be pests in agriculture or forestry, e.g. the winter moth or the hemlock looper. The adults are usually active during the night.
Their size is variable and the wingspan ranges from 10 to 70 mm. At rest their wings are spread out flat on the surface. The wings can be reduced in females. The caterpillars are slender with abdominal legs present only on the 6th and 10th segments. They move by the body forming a loop (loopers).
For details see the respective page in Wikipedia.
The following genera and individual species are currently entered under this family: