Moth borer

The larvae of this group of moth borers do damage to a range of stressed native trees. Some eat bark and can ringbark stems, causing death of the section. Others eat leaves, which they drag to the entrance of tunnels. The bark-eating larvae form nests of bark and droppings bound together by a web (see photo).
To get rid of these pests, prune off the webbing and destroy the larvae. Also remove damaged sections of bark. If twigs and foliage are damaged, prune them off and look for tunnel entrances. Poke a piece of fine wire into the holes as far as it will go. Remove the wire, and then seal the holes with putty, Blu Tack, or fine clay.
Attack by this pest is an indication that the plant is stressed and low on nutrients. Apply a complete fertiliser suitable for natives. Give the tree a drink of seaweed extract tea. Do not allow grass to grow close to the tree. Check drainage, and improve watering, if necessary. Use leaf mould as mulch around these plants.
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2 thoughts on “Moth borer

  1. this is very interesting and I dont think many people are aware of it. the secret with all highly stressed plants I think, is to apply the seaweed extract tea on a little but often basis (weak solutions) rather than one heavy dose, typically once every 10 to 14 days is ideal.

  2. Jim, the organic approach to pest problems is to look at why a plant is stressed and attracting pests and/or disease, and correct the the problem, which is most commonly soil-based. Seaweed extract tea can be part of the treatment and “weak black tea” strength that I recommend, or “very weak black tea” for seedlings is not a heavy dose (See post on seaweed in the garden – Healthy soil category.) I regularly get e-mails from gardeners with pest or disease problems that assure me they have been applying seaweed every fortnight, or so.
    As a preventative, plants should not require more than a couple of doses of seaweed “tea” per annum to remain healthy. The reason for this is that some seaweed products contain a considerable proportion of potassium, and too much potassium in soil can prevent plants absorbing calcium and magnesium – thereby causing a different range of problems. Seaweed extracts also contain a full range of trace elements that are only required by plants in tiny amounts. For some trace elements, a level slightly above a plant’s requirement can be toxic, and applications of seaweed extract tea can be overdone. I guess we’ll have to agree to disagree on how often seaweed extract should be applied.

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