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Family Geometridae - Geometrid Moths

Bad year to be a tree 1 - Operophtera brumata Caterpillar Filament Bearer, 10 days after collection - Nematocampa resistaria Caterpillar with Arrows - Eupithecia Hodges#6332 Rearing Cycle - Psamatodes abydata A Synchlora Accessorizes: Series - Synchlora Geometrid moth larvae Inchworm on wild sarsaparilla - Iridopsis ephyraria
Show images of: caterpillars · adults · both
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Geometroidea (Geometrid and Swallowtail Moths)
Family Geometridae (Geometrid Moths)
Other Common Names
geometer moths
measuringworms (larvae)
inchworms (larvae)
loopers (larvae)
spanworms (larvae)
Synonyms and other taxonomic changes
Geometridae Leach, 1815
Explanation of Names
Geometridae from the type genus Geometra (Linnaeus), Greek meaning "to measure the earth," referring to the larva, or inchworm, as they move in a looping fashion. (1)
1441 species in 5 subfamilies in our area according to Pohl et al. (2); about 35,000 species worldwide.
Adults small to medium-sized (wingspan 15-50 mm)
Below is a guide to the local subfamilies of Geometridae. The images included are meant to be illustrative of the general appearance of each subfamily as an aid for narrowing down possibilities for identification. While the commonest elements of forewing maculation in each subfamily are represented, many patterns are not.

Adult - usually have slender bodies and relatively large, broad forewings, often crossed by thin wavy lines; females of some species are wingless or have flightless atrophied wings. When at rest, many geometrid moths hold their wings away from the body and flat against the substrate (in contrast to most noctuid moths, which tend to fold their wings over their abdomen); some species/genera hold their wings in a characteristic position such as: flat & at right-angles to the body, or inclined 45 degrees above horizontal, or vertically over their back like a butterfly. Forewing cubitus vein appears 3-branched; hindwing subcostal vein bends abruptly downward at base.
Larva - generally have only two pairs of prolegs (at the hind end) rather than the usual five pairs in most lepidoptera; the lack of prolegs in the middle of the body necessitates the peculiar method of locomotion, drawing the hind end up to the thoracic legs to form a loop, and then extending the body forward.
Throughout North America and the world.
Larvae found on host plants in various vegetated habitats. Adults usually nearby, but most are nocturnal and attracted to light; a number of species are day-flying.
Most larvae feed on the leaves of woody plants (coniferous and deciduous trees, shrubs); some species eat herbaceous plants. Many species are economically important pests of fruit trees, forest trees, and berry crops.
Life Cycle
Click on each image below to view Life Cycle series.
See Also
The genus Zale in the Erebidae, which has pretty much the same characteristic outline as the Geometridae:

The genus Sigela in Erebidae also looks very similar:

Print References
Packard Jr., A. S. 1876. A monograph of the Geometrid moths or Phalaenidae of the United States. Rep. U.S. Geol. Geog. Surv. Terr. 10: 1-607, pl.1-10
Prout, L. B. 1913. Lepidoptera Heterocera. Fam. Geometridae. Subfam. Hemitheinae. Genera Insectorum, fasc. 129: 1-174, pl. 1-5
Internet References
pinned adult images and provincial/territorial lists of the 500+ species in Canada (Troubridge and Lafontaine, The Geometroidea of Canada)
live larva images of 38 eastern NA species, plus descriptions and information on biology etc. (geometrid Caterpillars of Eastern Forests; US Geological Survey)
Works Cited
1.An accentuated list of the British Lepidoptera, with hints on the derivation of the names.
Anonymous. 1858. The Entomological Societies of Oxford and Cambridge.
2.Annotated taxonomic checklist of the Lepidoptera of North America, North of Mexico
Pohl, G.R., Patterson, B., & Pelham, J.P. 2016.