The borer is the larval stage of the clearwing moth.
|Description of adult|
The adult borers that tunnel in the crotches of lychee trees are small, yellow and black clearwing moths that despite flying during the day, are seldom seen.
The larvae of the clearwing moth are a dirty-white colour with a brown head. They grow to about 12 mm in length.
The clearwing moth lays its eggs in cracks in the bark. On hatching, the larvae tunnel through the bark and top layer of wood. In the process, a covering of faeces mixed with webbing is produced, which protects the larva, under which it pupates. This accumulation of faecal matter hides the presence of the insect. There are several generations per year.
In all lychee and longan growing districts in Queensland
Lychee, longan, persimmon, soap tree (Alphitonia excelsa), Ficus sp., Wisteria and Calliandra.
Minor and sporadic pests.
The clearwing moth can be a minor problem in lychees but more so in persimmons. The larva (caterpillar) of the clearwing moth bores into the crotches of branches. Frass collects in the webbing covering the area of infestation. Indications of infestation and activity are the sudden death of part of a branch, and affected branches cracking and falling off.
No satisfactory action level is available for this pest.
Scrape the infested areas clean to remove and kill the borers. Seal the wounds with plastic paint or a tree sealing compound to aid recovery. Inspect trees regularly for signs of damage so that treatment can be applied before the problem gets too severe. Check very thoroughly when trees are dormant, as it is much easier to see the damage. Where possible, check every crotch on every tree. The pest is generally well controlled naturally by beneficial insects unless affected by the overuse of disruptive chemicals.
You may be able to control clearwing moth borers with pheromones, which disrupt mating in the moths. This small tube dispenses pheromones and is placed in the orchard among the trees.
Remove and destroy affected branches.
A small, unidentified wasp often heavily parasitises the clearwing moth larvae.
Chemical - registrations and permits
Check the Australian Pesticides & Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your state or location. Always read the label and observe withholding periods.