Teredo Borer

People may or may not be aware, but Preschem is part of a business group, that includes Outlast Timber in Mordialloc. Recently, the author of this post had to visit them and noticed two large 350 x 350 square ironbark posts that were riddled with Teredo Borer. The common name of this timber pest is Shipworm.

As you can see, the damage to these marine piles that were turned into square posts, is quite extensive. In some of the photos, you can see the pink opaque looking jelly, which is the Teredo Borer being cut in half when the posts were machined from the round pile. And the white residue along the galleries, are the remnants of this destructive timber pest.

Teredo Borer are actually molluscs that has no hard shell, except in their “valves”, which is what they use to rasp and bore through submersed wood. The wood is their food and it’s processed internally, assisted by bacteria in their gut, that breaks down cellulose, thus sharing a symbiosis of digestive function. They can grow up to 1m, through most adult shipworm, are typically10-15cm long.

Teredo Borer are very difficult to control, and typically marine piles made out of softwood are treated to H6 as per AS 1604, which offers about 25 years of service life, or special marine paints that contain very toxic active ingredients. The other option is to select extremely hard, dense timbers, such as ironbark, tallowood and turpentine. Terpentine is preferred if available, as it has a high silica content, which is thought to be the reason why it has excellent Teredo Borer resistance.

Unfortunately, Preschem doesn’t manufacture a product that will eradicate or protect marine timbers from Teredo Borer, but these photos do show quite spectacularly the damage that they can do.

The posts were quickly sold as landscaping timbers, and the galleries will make a very interesting feature and conversations.