Information

The geometer moths or Geometridae are a family of the order Lepidoptera. A very large family, it has around 26,000 species of moths described (over 300 of which occur in the British Isles). A well-known member is the Peppered Moth, Biston betularia, which has been subject of numerous studies in population genetics. Several other geometer moths are rather notorious pests.

Many Geometrids have slender abdomens and broad wings which are usually held flat with the hindwings visible. As such they appear rather butterfly-like but in most respects they are typical moths: the majority fly at night, they possess a frenulum to link the wings and the antennae of the males are often feathered. They tend to blend in to the background, often with intricate, wavy patterns on their wings. In some species, females have reduced wings (e.g. winter moth and fall cankerworm).

Most are of moderate size, about 3 cm in wingspan, but a range of sizes occur. They have distinctive paired tympanal organs at the base of the abdomen (lacking in flightless females).

The name "Geometridae" ultimately derives from geometer ("earth-measurer"). This refers to the means of locomotion of the larvae or caterpillars, which lack most of the prolegs of other Lepidopteran caterpillars. Equipped with appendages at both ends of the body, a caterpillar will clasp with its front legs and draw up the hind end, then clasp with the hind end (prolegs) and reach out for a new front attachment - creating the impression that it is measuring its journey.

The caterpillars are accordingly called loopers, spanworms, or inchworms. They tend to be green, grey, or brownish and hide from predators by fading into the background or resembling twigs. Some have humps or filaments (see Filament-bearer image). They are seldom hairy or gregarious. Typically they eat leaves. However, some eat lichen, flowers or pollen. Some, such as the Hawaiian species of the genus Eupithecia, are even carnivorous.

The placement of the example species follows a 1990 systematic; it may be outdated. Families are tentatively sorted in a phylogenetic sequence, from the most basal to the most advanced.

Traditionally the Archiearinae were held to be the most ancient of the geometer moth lineages, as their caterpillars have well-developed prolegs. However, it nowadays seems that the Larentiinae are actually older, as indicated by their numerous plesiomorphies and DNA sequence data. They are either an extremely basal lineage of the Geometridae – together with the Sterrhinae –, or might even be considered a separate family of Geometroidea.

As regards the Archiearinae, some species that were traditionally placed therein actually seem to belong to other subfamilies; altogether it seems that in a few cases, the prolegs which were originally lost in the ancestral geometer moths re-evolved as an atavism. 

Subfamilies in this Superfamily

Alsophilinae, Archiearinae, Desmobathrinae, Ennominae, Geometrinae, Larentiinae, Oenochrominae, Orthostixinae, Sterrhinae

List of Species We Have Photos and Information On

Geometer Moths
Image/Page Link	Common Name	Scientific Name
	Brimstone Moth	Opisthograptis luteolata

(c) David McCormick 2008