Blueberry leaftier

Blueberry leaftier (Croesia curvalana) is an exotic plant pest not present in Australia. This insect is a serious threat to Australia’s blueberry industry.

Blueberry leaftier is a small moth species and has been labelled one of the most destructive pests of blueberry crops in North America.

Notifiable status

Blueberry leaftier (Croesia curvalana) is not a notifiable plant pest in NSW.

However, if you suspect Blueberry leaftier (Croesia curvalana):

• Call the Exotic Plant Pest Hotline 1800 084 881
• Email biosecurity@dpi.nsw.gov.au with a clear photo and your contact details

A full list of notifiable plant pests and diseases can be found in Schedule 2 of the NSW Biosecurity Act 2015.

Description

Adult

Adult blueberry leaftier moths are about 6 mm long with a wingspan 14–16 mm. When the moths’ wings are folded the main colour that can be seen is rust red-brown bordered by yellow margins. The body and head are also yellow in colour and two small yellow spots can be seen in the centre of the rust coloured patch (Figure 1).

Immature stages

The eggs of blueberry leaftiers are approximately 0.6 mm in diameter and oval in shape. The eggs are white in colour when they are first laid, but turn brown after three days.

Blueberry leaftier larvae are 5–7 mm in length. Young larvae are cream coloured with a black head. Older larvae become yellowish with a cinnamon brown head.

Damage

Blueberry leaftier larvae cause damage by feeding on developing flower buds, leaves and flowers.

Young larvae cause the most serious damage by burrowing into developing flower buds to feed. They have been recorded to affect up to 20% of buds.

Older larvae feed on the leaves and flowers. In severe outbreaks defoliation can be close to 100%.

Lifecycle

Female blueberry leaftier moths lay single eggs on leaf litter around the base of host plants. The eggs are the overwintering stage of the lifecycle and greater egg hatch is observed when eggs have been exposed to a period of ‘chilling’.

The eggs hatch mid-late spring. Newly hatched larvae climb into the blueberry plant to burrow into flower buds and begin to feed.

Larvae go through four growth stages with second, third and fourth stage larvae moving from the flower buds to feed on expanding leaf buds, young leaves and mature flowers. The larvae will use silk to bend leaves to form a protective shelter while they feed (Figure 2).

Pupation occurs in early summer, usually within the leaf shelter.

Host range

Blueberry leaftier is a known pest of low bush blueberry Vaccinium angustifolium and high bush blueberry Vaccinium corymbosum. Little research is currently available on other potential host species.

Spread

Blueberry leaftier moths can spread short distances by flying, though they usually restrict flight to within or beneath the canopy of host plants.

Long distance spread of blueberry leaftier is most likely to occur with the transportation of infested plant material.

Distribution

Blueberry leaftier is native to and established across North America, including the United States and Canada.

Actions to minimise risk

Put in place biosecurity best practice actions to prevent entry, establishment and spread of pests and diseases:

• practice “Come clean, Go clean”
• ensure all staff and visitors are instructed in and adhere to your business management hygiene requirements
• source propagation material of a known high health status from reputable suppliers
• monitor your plants regularly
• keep records