Geometrid moth

Geometridae spp.

1. Identification

• Common name: Geometer moth; Inchworms
• Scientific name: Geometridae spp.
• Order: Lepidoptera
• Family: Geometridae

2. Pest description

• Caterpillars with an elongated and slender body, moving in a “pinning step” or “measuring” manner, a typical characteristic of the family.
• Variable colour (green, brown or greyish), often with excellent camouflage among branches and leaves.
• Adults generally with broad and slender wings, with discreet patterns that aid camouflage.
• Highly diversified species-group, with numerous defoliating species in agricultural, forestry and ornamental crops.
• Caterpillars feed on young leaves, and can cause significant defoliation in intense attacks.

3. Main hosts

• Deciduous trees (oak, chestnut, birch).
• Various fruit trees (apple, pear, stone fruit).
• Forestry and ornamental species.
• Spontaneous plants that act as alternative hosts.

4. Symptoms and damage

• Irregular perforations and cuts on the leaves.
• Partial or total defoliation in cases of high population density.
• Reduction of plant vigour and decrease in annual growth.
• More severe damage in young or weakened plants.
• Presence of well-camouflaged caterpillars on the branches and leaves.

5. Biological cycle

• Eggs laid on the bark, branches or leaves, depending on the species.
• Caterpillars emerge in spring and feed for several weeks.
• Pupation occurs in the soil, in the litter or in bark crevices.
• Adults emerge in summer or autumn, varying between species.
• Generally one generation per year, although some species may have more.

6. Monitoring

• Direct observation of caterpillars and foliar damage.
• Search for eggs and young caterpillars on branches and leaves.
• Light traps to detect adults.
• Periodic assessment of defoliation in sensitive stands.

7. Management measures

• Cultural: removal of infested branches; promotion of plant diversity; maintenance of plant health.
• Preventive: regular monitoring during spring; early identification of foci.
• Biological: application of Bacillus thuringiensis on young caterpillars; promotion of natural parasitoids and predators.
• Integrated protection: judicious application of authorised insecticides when intervention thresholds are reached; integration of cultural, biological and chemical measures.

Bibliographic references

• EPPO Global Database – Geometridae spp..
• CABI – Invasive Species Compendium – Geometridae spp..
• Carter, D. J. (1984). Pest Lepidoptera of Europe. Dr. W. Junk Publishers.
• Hill, D. S. (1987). Agricultural Insect Pests of the Tropics and their Control. Cambridge University Press.