Tortix Moth, Leafroller Moth, Webber Moth
Tortricidae is a family of moths, formerly known as 'leafroller moths'. This name refers to the moth larvae, who use silk to curl plant leaves at the margins. They graze on leaf surfaces and in some cases, the fruits too. Other species opt for different feeding strategies, where the larvae are primary leaf miners or gall formers. Tortrix moths can be a tricky pest to eradicate because they use the host plant as an added layer of protection against pesticides and other control methods. There are roughly 40 species of Tortrix Moths in South Africa.
Many species of Tortrix Moth are pests as larvae.
Adults: Depending on the species, appearance can vary. The adults usually are quite drab looking; the false codling moth is a good example for reference. They are generally mottled with browns and greys, although some can be colourful. The wings usually are quite broad, almost appearing rectangular. They are small to medium-sized (wingspans 3cm or less). Their resting posture is distinctive, where at rest they hold the wings like a pointed roof above the body. Larvae: The larvae are often cryptic, forming refuge from their silk. They do this using leaves of the host, either rolling leaves with silk or burrowing into the leaves and fruits. Some species can cause galls to form on the host. Galls are abnormal tumours, produced by the plant in response to larvae on the host. The larvae will feed and burrow within the gall, where they remain protected until fully grown. Pupae: Larvae will either pupate underground or beneath the leaves of the host.
Sticky silk webbing in the leaves and branches. Caterpillars in rolled up leaves. Abnormal growths form instead of new growth. Meandering, silver/brown trails on leaves. Premature leaf fall or fruit fall. Brown/black lesions in fruits. Secondary fungal or bacterial infections.
It's thought that established plants can withstand Tortrix Moth infestations. Lighter infestations can be managed by picking off the damaged leaves and squishing the caterpillars inside. Sometimes, pheromone traps are commercially available to gardeners. These not only help a gardener monitor their gardens moth population but can reduce the number of males in the local area, jeopardising a females mating success. For heavier infestations where there's damage to leaves and fruits, prune the infested tree branches and dispose of them accordingly.
Pesticides may be used sometimes, although, it can sometimes be too difficult (and expensive) to cover a whole infestation and penetrate the leaf rolls, galls and mines. The earlier treatment is always preferred because the larvae are more vulnerable at this time. Gardeners should take care to avoid spraying any flowers because chemicals can be harmful to pollinators. Organic pyrethrums are proposed as more environmentally benign than synthetic insecticides. Synthetic pyrethroids are more aggressive in their mode of action but can be applied to plants less frequently. Please consider if chemical control is necessary. If a chemical option is sought, please take care to follow the manufacturers' instructions. Check with your local regulating body for guidance on active ingredients and their authorisation for use. If you're unsure, you can consult with your local gardening centre or ask the Candide community for assistance!