Nov 20, 2011 – Troubles With Tribbles?


I have a client who claims that they have gribbles, which are wood eating crustaceans, Genus: Limnoria or L. lignorum, (according to their research on the internet). I have not been to the site to identify it. My questions is, is this pest indigenous to Malibu, CA, and if so how do I treat it?


Well, I sure learn something new every day, and my first thought was that here was another great example of the power of the internet, allowing people to find justification for their imaginary problems. (It also reminded me of that old Star Trek episode and the infestation of tribbles on the Enterprise - "gribbles"?).

However, turns out that there is such a thing as a Gribble, and the Latin name you provided is valid - Limnoria lignorum is a marine crustacean (related to pillbugs and sowbugs) that does feed within pilings and other wood members where the wood meets the ocean. When their numbers are really high they can do serious damage to the pilings, and even leave behind a hollow timber that no longer provides any structural strength. While I cannot swear they occur in Malibu it would be likely that they do, since Malibu is located right along the coast of southern California. The gribbles look very similar to sow bugs, and as we may know another name for sow bugs in many countries is "wood louse", so they are known to enter wood.

Control after-the-fact may be very difficult, as it would require treating a piling that is going to be in contact with the water in a short time. And, treating that piling below water line is probably impossible to do. Bora-Care may be one of the only wood preservatives that could actually penetrate deeply into logs, and it is labeled for use on "pilings". However, the intent is to treat that piling prior to its being sunk into the ground for holding up boat docks. Any surface coating currently on an existing piling would prevent the use of Bora-Care, as would any contact with water within 24 hours, seriously limiting its use on pilings.

This may be something beyond the scope of our normal pest management, and perhaps should be referred to a company that specializes in boat docks and their repair or installation. I was unable to find anything on the internet that offered any valuable tidbits on the management of these arthropods.

As a followup, it turns out that this client likely has Amphipods - little garden "shrimp" that commonly occur in damp areas in landscape, and which are harmless scavengers that really do not require control, other than removing their hiding places.

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