Leaf-roller moths (tortricids)

Identification

The caterpillars roll, fold and glue leaves together with a webbing of silk threads, creating shelters in which they feed hidden from view. When disturbed they wriggle violently backwards and drop on threads, which aids their identification; the adults are small moths with a bell-shaped outline of the folded wings. The host plants are fruit trees (apple, pear, plum), ornamental shrubs and roses. Symptoms: the caterpillars chew leaves, flower buds and fruit set and damage the skin of ripening fruit, reducing its value. The name covers many species of the family Tortricidae with a similar way of life - among them the summer fruit tortrix (Adoxophyes orana) and the rose tortrix (Archips rosana). The caterpillars are slender, up to about 1.5-2 cm long, usually light or olive green with a darker head and prothoracic plate, and very active. The moths have a wingspan of about 15-25 mm; at rest they fold the forewings roof-like, giving the characteristic bell-shaped (trapezoidal) outline, and their pattern is greyish-brown with a darker cross-band. The life cycle depends on the species: leaf-rollers overwinter as eggs laid in patches on the bark or as young caterpillars hidden in bark crevices and under bud scales; in spring they bore into the swelling buds, then move onto the leaves and fruit set, and one or two generations develop over the season. A diagnostic feature on pome fruit is the attachment of a leaf to the fruit and the shallow grazing of the skin beneath it, which leaves irregular, corky scars while the flesh deeper inside remains intact. On roses and ornamental shrubs the symptom is rolled young leaflets bound with webbing and hollowed-out buds.

Treatment

The basis is collecting and destroying rolled leaves together with the caterpillars hidden inside, and spraying with Bacillus thuringiensis or spinosad at the early larval stage, before they retreat into the webbing. Pheromone traps serve to monitor moth flight and time the treatments, and natural enemies, predatory and parasitic insects, should be protected. The key to effectiveness is timing: sprays act only on exposed caterpillars - just after they hatch from the eggs or in spring, when the overwintering larvae emerge from their shelters and feed on the buds; once the leaf is rolled, the webbing shields them from the spray liquid. Treatments are therefore timed according to catches in pheromone traps (separate dispensers for the individual species) rather than by guesswork. In small plantings and on roses, consistent removal of rolled leaves and Bacillus thuringiensis biopreparations are enough; spinosad also helps, although it is toxic to bees while wet, so it is applied in the evening and outside flowering. Under strong, recurring pressure, insect growth regulators (chitin synthesis inhibitors) are used, and broad-spectrum insecticides (e.g. pyrethroids) only as an intervention and with rotation of modes of action, because they wipe out natural enemies and quickly lead to resistance. In larger orchards, the pheromone mating-disruption method works well. Support natural enemies - egg parasitoids (Trichogramma), ichneumon wasps, predatory bugs and insectivorous birds (nest boxes), which keep leaf-roller numbers in check.

How to tell it apart from look-alikes

Feature	Leaf-roller moths (tortricids)	Codling moth
Leaf damage	Rolled leaves glued together with webbing, with a caterpillar feeding inside	Practically no leaf damage - the caterpillar enters the fruit right away
Fruit damage	Superficial, shallow grazing of the skin (often under an adhering leaf); the flesh beneath is healthy	A tunnel bored to the seed core; brown frass falls out of the hole (the 'worm in the apple')
Caterpillar's hiding place	Inside a rolled leaf or webbing	Inside the fruit
Feeding time and phenology	Feeding as early as early spring on bursting buds and young leaves; 1-2 generations	Arrival and egg-laying only after flowering; the larvae bore into the fruit in summer and late summer
Reaction to disturbance	Wriggles violently backwards and drops on threads	Hidden in the fruit, invisible from outside

Control — organic and chemical methods

Organic and biological methods

Method	How it works	When to use
Collecting and destroying rolled leaves, cutting out infested shoots	Manual removal of caterpillars hidden in the webbing, where sprays do not reach; effective with a small number of plants and on roses.	Throughout the season, whenever rolled leaves appear
Bacillus thuringiensis (Bt) biopreparation	The bacterial toxin acts by ingestion only on feeding young caterpillars; it spares bees and beneficial insects.	After larval hatch or in spring, when the caterpillars feed exposed on buds and young leaves
Protecting and supporting natural enemies (Trichogramma, ichneumon wasps, birds)	Egg and caterpillar parasitoids and insectivorous birds limit the population; a preventive, supporting method that does not eliminate a heavy infestation.	Continuously - avoid broad-spectrum insecticides, put up nest boxes
Pheromones - trap monitoring and mating disruption	Traps determine the flight period and the optimal spraying moment; pheromone disruption disturbs pair mating, effective mainly on large areas.	Traps from the start of moth flight; disruption throughout the flight period

Chemical methods

Method	How it works	When to use
Spinosyns (spinosad)	A contact and stomach neurotoxin against young caterpillars; toxic to bees while wet - apply in the evening and outside flowering.	At the early larval stage, according to trap signalling
Insect growth regulators (IGR) or pyrethroids according to threshold	IGRs disrupt larval moulting; contact and stomach pyrethroids only as an intervention, because they destroy natural enemies and promote resistance.	As an intervention after the damage threshold is exceeded, with rotation of modes of action

We give active-ingredient groups and modes of action, not brand names — specific products and their approval vary by country and are sometimes withdrawn. Always check and follow the current label.