Chewing damage is visible on young leaves, stems, flowers and fruits. Young larvae feed on the underside of leaves where they make small perforations. As the larvae grow older, whole leaves, stalks and also flowers and fruits may be severely damaged. A series of holes and superficial scratching and tunnels are visible on the fruit surface. Damaged tissues and frass are colonized by opportunistic pathogens that favors rotting. Thus, even slight infestations of older larvae can be harmful for the crop. They have a variety of host plants, including tomato, pepper, potato, lettuce, cucumber, onion, cabbage and cauliflower.
Damage is caused by the caterpillar of the bright line brown eye moth, Lacanobia oleracea. It prefers humid and nutrient-rich sites and is found in a variety of habitats such as greenhouses, on farmland, along rivers or forest clearings. The adult moth has a wing span of about 35-45 mm, and a light brown body with some slightly darker specimens. Forewings are dark reddish-brown marked with a prominent light orange, kidney-like blotch. A white, bright line incorporating a ‘W’ close to the edge is another marked feature. The hindwings are grey, darker toward the edge. Females lays eggs in groups of about 150 units and place them on the leaves undersides of their host plants. Caterpillars reach a size of up to 5 cm. Their color ranges from green to dark brown, with white and black speckles and a yellow stripe on each flank.
In some cases, the introduction of Trichogramma parasitoid wasps (T. evanescens) or the predatory bug Podisus maculiventris reduces caterpillar populations. Use insecticides containing Spinosad or Bacillus thuringiensis (Bt) that do not persist in the environment. A concentration of 0.1%. sprayed as soon as the larvae are discovered and repeated twice is a good alternative to chemical control of these larvae.
Always consider an integrated approach with preventive measures together with biological treatments if available. In the case of this moth, the efficacy of alternative products such as spinosad and Bt often does not justify the use of chemical treatments. If appropriate, products based on alpha-cypermethrin, beta-cyfluthrin, bifenthrin, cypermethrin, deltamethrin, diflubenzuron, fenpropathrin, lambda-cyhalothrin, teflubenzuron can be applied. It is important to use pesticides in the frame of well-planed integrated management strategies to avoid deleterious effects to beneficial insects.