Lightbrown apple moth - Description - Adults - Eggs - Larvae - Pupae - Damage

Adults Lightbrown apple moth male adults have a forewing length of 6-10 mm with a light-brown area at the base distinguishable from a much darker, red-brown area at the tip. The latter may be absent in some males, the moth appearing uniformly light-brown, as in the females, with only slightly darker oblique markings distinguishing the area at the tip of the wing. Females have a forewing length of 7-13 mm. Colour varies from a uniform light brown, with almost no distinguishing markings, to the typical oblique markings of the male colouration. Males have a 'fan' of large scales at the tail end of the abdomen (body) whereas the brown ovipositor can be seen when viewing the tip of the female abdomen from below. Hindwings of both sexes are a uniform or mottled, pale brown, but are hidden beneath the folded forewings when the adult is at rest. The length of the resting moth is about half the wingspan.

Eggs of all leafroller species are laid in rafts or batches of 2 - 170, usually on the upper surface of host plant leaves. The eggs are flat, and with a pebbled surface. They overlap each other within the raft to form a smooth mass. This makes it difficult to distinguish the eggs from the surrounding leaf surface. Eggs of lightbrown apple moth are approximately 0.7 mm by 1.0 mm. They are initially white to pale green and change to a paler yellow green as they develop. Prior to hatching the dark head of the developing caterpillar is visible through the egg wall, giving the egg batches a blotchy or speckled appearance. Eggs parasitised by minute wasps (e.g. Trichogramma spp.) are black just prior to wasp emergence.

Larvae [caterpillars] of lightbrown apple moth are difficult to distinguish from the larvae of greenheaded and brownheaded leafrollers, when occurring together in the same habitat. However, their colour, markings and size provide some distinguishing features. There are five or six larval instars (stages) in all species. The first larval instar is about 1.5 to 2.0 mm long and has a dark brown head; all other instars have a light fawn head and prothoracic plate [plate behind the head], although overwintering larvae are darker. The final instar larvae range from 10 to 18 mm in length. The body of a mature larva is medium green with a darker green central stripe and two side stripes. This green longitudinal striping is helpful for distinguishing lightbrown apple moth caterpillars from the other (native) leafrollers.

Pupae The pupa (chrysalis) is at first green, but soon becomes brown after rapidly hardening, and then darkens during development. The pupa is typically found in a thin-walled silken cocoon between two leaves webbed together, and is usually 10-15 mm long; the female pupae are larger than those of the male. Males and females can be distinguished by examining the pupa from the lower surface. In the female, three dark segmental bands are visible beyond the tip of the wing cases whereas there are four in the male. At the end of the abdomen, two prominent broad-based laterally-projecting spines and a number of hooks support the pupa in its cocoon. Each abdominal segment also has a series of short, backward-projecting spines that are used by the pupa to move partially out of its cocoon prior to moth emergence.

Damage All five species of leafroller larvae cause similar damage to foliage and fruits; there is no way of distinguishing the damage of different species. Early instars often settle on the under surface of leaves close to the main veins, where they construct silken shelters and feed on the leaf tissue; this feeding typically creates small windows in the leaves. Other young larvae are commonly found on the shoot tips or areas of new growth, where they web the leaves together with silk. A third settlement site is the calyx of fruits such as apple, where their presence is detected only from observing the fine silken webbing among the sepals. Larger larvae migrate from these settlement positions to construct feeding niches between adjacent leaves, between a leaf and a fruit, in a developing bud, or on a single leaf, where the leaf roll develops. The late stage larvae feed on all leaf tissue except main veins. Buds of deciduous host plants are especially vulnerable to attack in the winter and early spring, when the interior of the buds may be eaten.

Surface fruit damage is common in short-stemmed apple varieties which form compact fruit clusters. Leaves are webbed to the fruit and feeding injury takes place under the protection of the leaf; or larvae spin up between fruits of a cluster. Small, circular 'stings' are caused by young larvae biting through the skin. This is typically on the green side of the apple (such as where a leaf and fruit have come in contact), in contrast to codling moth stings which are on the ripe side of the fruit. In crops such as kiwifruit, plum, grapefruit, and apple, the maturing fruit produces a layer of corky tissue over the damage by leafrollers; this helps prevent secondary infection by pathogens. Internal damage to apple, and pear fruits is much less common than surface damage, but a young larva may enter the interior of an apple or pear through the calyx. The presence of extensive silk distinguishes this damage from that of codling moth. In addition, the excreta (frass) of leafrollers occur as distinct pellets and are usually ejected and scattered on to the outside of the fruit. In contrast, codling moth frass is pushed to the surface in a sticky mass where it is often seen at the entry hole. Leafrollers can cause internal damage to apricots, peaches, and walnuts as well as apples.