HortFACT
Identification
Adults are extremely variable in colour and forewing pattern, and may be difficult to distinguish from other leafroller moths. In both sexes the forewings are typically walnut brown, but vary from dark brown to a pale fawn, and are sometimes twotone. 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 about one-third the distance from head to wingtip. 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. Hindwings are a uniform, 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. Adults are active from evening through to the early hours of the morning.
Eggs measure approximately 0.7 mm by 1.0 mm and are laid in batches of 2 to 150 overlapped to form a smooth mass on the hostplant leaf. Initially pale green, they change to pale yellow before hatching. The egg batch is usually very difficult to distinguish from the surrounding leaf.
The larva, or caterpillar, after hatching is about 2 mm long with a pale-green head and body. In the second instar (growth stage) the head becomes black, and through subsequent instars changes from dark brown to reddish brown. The mature larva may have faint red stripes on its head, and is up to 20 mm long. The body remains green throughout the larval period of five or six instars.
The pupa is bright green when first formed, but quickly changes to pale brown. Its colour progressively deepens to very dark brown just before the adult emerges. The pupa is typically found in a thin-walled silken cocoon between two leaves webbed together, and is usually 10-13 mm long.
Host plants
This leafroller has a wide range of native and introduced host plants, and is an important horticultural pest. Economically important host plants include kiwifruit, pome (pip) and stone fruit, grape, feijoa, and many varieties of citrus and berryfruit crops. Other host plants include pohutukawa, karaka, mahoe, poroporo, coprosma, willow, honeysuckle. privet, poplar, eucalyptus, ivy, cyclamen, orchids, roses, and clover.
Damage
Larvae damage the leaves, fruit, and buds of host plants. It is not possible to distinguish this damage from that of the other two common leafroller species, the light brown apple moth and the greenheaded leafroller. Young larvae are commonly found on the shoot tips or areas of new growth, where they web the leaves together with silk. Early in the growing season buds of deciduous host plants may be penetrated and the interior eaten. Young larvae in a rolled leaf feed only on the inner surface of the leaf, whereas mature larvae eat right through the leaf.
Both young and mature larvae are capable of webbing leaves to the fruit and then superficially damaging the fruit. In crops such as kiwifruit, plum, grapefruit, and apple the maturing fruit produces a layer of corky tissue over the damage; this helps prevent secondary damage due to disease. The calyx of various fruits, especially pip fruits, may be invaded by young larvae but show no external damage.
Distribution
This species is found only in New Zealand, and occurs in all horticultural areas. Larger populations are concentrated in the northern half of the North Island, where it is the dominant leafroller. This dominance is progressively reduced southward through New Zealand.
Life cycle
| Egg |  |
| Larvae | |
| Pupae | |
| Adult | |
| Month | |
| Note: Coloured bars indicate periods of peak activity in each of the life cycle stages | |
In the Auckland area there are four to six generations annually. Because these overlap, every stage of the life cycle may be found at all times of the year. As with the greenheaded leafroller in this area, there is a peak in numbers of adults flying in winter The progeny of these moths fly in spring, and produce the young larvae which infest new growth on many host plants. During summer there are two to four more peak infestations of young larvae. The timing of such peaks varies from host plant to host plant and between localities, producing overlap from one generation to the next. The life cycle chart illustrates this continual overlapping of summer generations and the overall lack of distinct peaks for the Auckland area. The timing of damage, represented by the central ring, is consistent with deciduous hosts like apple and plum. During winter, larvae survive on alternative hosts such as evergreen native trees and shrubs or ground-cover plants.
Further south the generations are more distinct. and vary according to latitude. Hawke's Bay has four to five each year, Nelson has three to four, and Canterbury two to four.
C. J. GREEN