T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Geometer moths (Family: Geometridae) Emerald moths

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Lepidoptera
(unranked): Macrolepidoptera
Superfamily: Geometroidea
Family: Geometridae
Common names: Geometer moths, Emerald moths

Geometrinae is the nominate subfamily of the geometer moth family (Geometridae). It is strongly split, containing a considerable number of tribes. Their scientific name derives from the Ancient Greek geo γη or γαια 'the earth' and metron μέτρων 'measure' in reference to the way their larvae, or inchworms, appear to "measure the earth" as they move along in a looping fashion. It’s a very large family; it has around 35,000 species of moths described.

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 row of bristles on the edge of the hindwing (frenulum) which keeps it in contact with the forewing. The antennae of the males are often feathered. They tend to blend into 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 centimetres in wingspan, but a range of sizes occur from 10–50 mm, and a few species (e.g., Dysphania) reach an even larger size. They have distinctive paired tympanal organs (hearing organ) at the base of the abdomen (lacking in flightless females).

A Geometridae caterpillar camouflages itself as a broken twig. The name "Geometridae" ultimately derives from Latin geometra from Greek γεωμέτρης ("geometer, earth-measurer"). This refers to the means of locomotion of the larvae or caterpillars, which lack the full complement of prolegs seen in other Lepidopteran caterpillars, with only two or three pairs at the posterior end instead of the usual five pairs. 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 after their characteristic looping gait. The cabbage looper and soybean looper are not an inchworm, but a caterpillar of a different family. In many species of geometer moths, the inchworms are about 25 mm long. They tend to be green, grey, or brownish and hide from predators by fading into the background or resembling twigs. Many inchworms, when disturbed, stand erect and motionless on the prolegs, increasing the resemblance. Some have humps or filaments. They are hairy or gregarious and are generally smooth. Typically they eat leaves. However, some eat lichen, flowers, or pollen. Some, such as the Hawaiian species of the genus Eupithecia, are even carnivorous. Certain destructive inchworms are called cankerworms.

Visit Landcare Research's Geometridae image gallery

Photos below are  of a few Geometridae moths species

Xyridacma ustaria

Xyridacma alectoraria female

Xyridacma alectoraria male