Forda marginata

Crusty pistachio-grass root aphid

Description

Forda marginata, known as the crusty pistachio-grass root aphid, primarily infests Pistacia species, particularly Pistacia terebinthus. It forms elongated, spindle-shaped galls along the edges of the leaves of its primary host. In autumn, winged alates leave the galls to migrate to their secondary hosts, which are grass species (Poaceae), where they establish colonies. In these colonies, Forda marginata reproduces parthenogenetically through the winter. This species follows a two-year life cycle in southern Europe, the Middle East, and northwestern India, alternating between Pistacia and grasses. In other parts of Europe, North America, and Asia, it completes its life cycle on grass roots without returning to Pistacia. Its presence is often noted in areas where grasses grow in disturbed soils, such as road edges or urban environments.

Symptom

Infestations of Forda marginata are marked by spindle-shaped galls along the leaf edges of Pistacia and discoloration or stunting of grass roots where colonies form.

Tree Species: Pistacia

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes