Black webspinner

The black webspinner (Oligotoma nigra) belongs to the order Embioptera, within the family Oligotomidae. These insects are unique due to their silk-spinning capabilities, which they use to construct elaborate galleries that protect them from predators and environmental stressors.

In agricultural settings, these pests are primarily known for feeding on bark, lichens, and mosses, but they can become significant pests when they turn their attention to cultivated plants. They are frequently observed causing damage to grapevines, citrus trees, and various ornamental shrub species in warm, arid climates.

The biology of Oligotoma nigra is defined by its social-like behavior and silk production. The life cycle consists of eggs, nymphs, and adults. Silk glands located on the forelegs allow all active stages to spin protective tunnels, which serve as their primary habitat and nursery areas during the growth and reproduction phases.

Damage occurs when the insects graze on the outer tissues of stems and bark, leading to lesions that weaken the plant's structural integrity. Furthermore, the persistent accumulation of silk webbing can restrict the normal transpiration of the plant, potentially leading to branch dieback and an increased susceptibility to secondary infections such as fungal pathogens.

Management strategies emphasize cultural controls, such as pruning heavily infested branches and removing older web structures to expose the insects. Chemical control, including the application of systemic or contact insecticides, is most effective when timed to coincide with the hatching of nymphs, as they are most vulnerable before establishing secure, extensive galleries.