Brownheaded leafroller - Description - Adults - Eggs - Larvae - Pupae - Damage

There are two species of brownheaded leafroller, Ctenopseustis obliquana and Ctenopseustis herana. Their appearance is identical at all stages - adult moths, eggs, larvae, or pupae. The two species produce different pheromones, and pheromone trapping enables the populations of each species to be monitored independently. In addition, the distribution of the species varies in different parts of New Zealand

Adults The moths of brownheaded leafroller are extremely variable in colour and forewing pattern. In both sexes the forewings are often walnut brown, but vary from dark brown (almost black) to a pale fawn, and have a variety of colour combinations. Females have a characteristic darker oblique mark halfway down the edge of each forewing. The body length is generally 8-12 mm and the wingspan 20-28 mm. Males too have an oblique forewing mark, plus a characteristic dark, transverse stripe (often black) across the front part of the folded wings about 2 millimetres behind the head. Their body length is generally 8-11 mm, and wingspan 17-24 mm. Adults often have other darker areas that vary in position, and in shade from pale to dark brown. 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 brownheaded leafroller are approximately 0.7 mm by 1.0 mm and the batches have a sparse coating of particles over the surface. They are initially pale green and change to a more 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] are difficult to distinguish from the larvae of lightbrown apple moth and greenheaded 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 pale brown head with a dark mark on each side and the body is often pale green. The head becomes strikingly black in the second instar, and changes again, through subsequent instars, from dark brown to reddish or pale brown. Body colour varies. The mature larva may have faint red or red-brown stripes on its head, and is up to 20 mm long.

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.