How harmful are woodlice on board?

Greenheart

Greenheart

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I've been a bit distracted for a couple of summers, and looking carefully at the Osprey's cockpit yesterday, I realised it is home to quite a few woodlice.

I had noticed them previously, but in a glassfibre boat with mainly encapsulated timber, I never thought anything about it.

But now I see countless tiny brown crumbs which must be woodlouse waste...so my cockpit must be their banqueting hall, parade ground and latrine. The boat is off the ground, so it would be tedious to crawl down the transom tubes and trailer-wheels in search of breakfast, then all the way back up later...

...they can only be eating the boat. There are odd bits of bare ply stiffening and iroko cleat backing-plates, which never get wet and so were never glassed-over or epoxied. But I thought woodlice favoured rotten wood - do I need to investigate the condition of the glassed-over wood ribs in the floor?

Has anybody had a boat damaged by woodlice before?
 
I don't really know, except that they are crustaceans. I found this, so maybe intact wood may be at risk. Another entry says that they also feed on their own faeces.
"We’re going to jump in with the most common question. What do woodlice eat? Woodlice will feed mostly on decomposing plant material and wood. They’re actually thought about as the recyclers of the insect world. They prefer damp environments, which they thrive in. If you have a compost bin, consider finding some woodlice around the garden. They will work wonders for your compost heap, and it may also stop them from being a nuisance in other areas of the garden. Don’t be worried though – it’s very rare a woodlouse will feast on your freshly planted flowers. "
 
dancrane said:
I've been a bit distracted for a couple of summers, and looking carefully at the Osprey's cockpit yesterday, I realised it is home to quite a few woodlice.

I had noticed them previously, but in a glassfibre boat with mainly encapsulated timber, I never thought anything about it.

But now I see countless tiny brown crumbs which must be woodlouse waste...so my cockpit must be their banqueting hall, parade ground and latrine. The boat is off the ground, so it would be tedious to crawl down the transom tubes and trailer-wheels in search of breakfast, then all the way back up later...

...they can only be eating the boat. There are odd bits of bare ply stiffening and iroko cleat backing-plates, which never get wet and so were never glassed-over or epoxied. But I thought woodlice favoured rotten wood - do I need to investigate the condition of the glassed-over wood ribs in the floor?

Has anybody had a boat damaged by woodlice before?
Click to expand...
I would not be complacent - speaking as someone who has just found active woodworm in the woodwork forming the framing for the GRP sink/galley, in a GRP catamaran.
 
The coprophagy has the benefit of recycling dietary copper, woodlouse blood (like that of marine crustaceans, at least one of which was their ancestor) being copper-based rather than iron-based.
 
Lots of interesting and informative replies in a short time, thank you.

neilf39 said:
You must have damp wood somewhere around the region you found them. Rain ingress or condensation? I would hunt it down and sort
Click to expand...

That is my conclusion too, though I had hoped I might be worried without reason.
 
Rubbing strake mossy?

Leaf mould in cockpit under grating boards?
Hydrozoan said:
The coprophagy has the benefit of...
Click to expand...
Ever noticed how in disaster stories, survivors always consider eating the cabin boy or other passengers first, before exploring that option? It appears cannibalism is the more socially acceptable option to admit up to.
 
Hallberg-Rassy said:
Rubbing strake mossy?

Leaf mould in cockpit under grating boards?

Ever noticed how in disaster stories, survivors always consider eating the cabin boy or other passengers first, before exploring that option? It appears cannibalism is the more socially acceptable option to admit up to.
Click to expand...

I like your thinking about the moss and leaf mould. But no, I had not given thought to the coprophagy vs. cannibalism question.

BTW, on the question of why some groups of animals have evolved to use hemocyanin with copper as the oxygen-binding metal, rather than haemoglobin/iron, it seems that the former may have advantages in cold, low oxygen conditions - though it has also been suggested that in the 'Oxygen Catastrophe' of 2.4bn years ago, a variety of biochemical methods to bind then-toxic oxygen may have evolved, which led in due course to a variety of oxygen-carrying molecules.

But I think we can rule out the woodlice nibbling Dan's prop for the copper.
 
My last boat was an insects paradise. So much so that my partner wouldn't sleep in it. The cockpit was shared by woodlice and a couple of woodlouse eating spiders which kept them down I guess.
Inside were normal spiders and other creepy crawlies. It was a part wooden boat which they love I guess. Live and let live has always been my philosophy.
 
I crewed on a large old wooden vessel, many years ago, and they were everywhere. We were banned from squashing them, the captain swore they were not partial to sound timber, and only consumed rot.
The best thing would be to capture one, and get his identity established, to learn of his probable diet!
 
Gary Fox said:
I crewed on a large old wooden vessel, many years ago, and they were everywhere. We were banned from squashing them, the captain swore they were not partial to sound timber, and only consumed rot.
The best thing would be to capture one, and get his identity established, to learn of his probable diet!
Click to expand...
True. They are the symptom of a problem, not its cause. Once I had a shed that was a real woodlouse hotel. It fell down.
 
dancrane said:
I've been a bit distracted for a couple of summers, and looking carefully at the Osprey's cockpit yesterday, I realised it is home to quite a few woodlice.

I had noticed them previously, but in a glassfibre boat with mainly encapsulated timber, I never thought anything about it.

But now I see countless tiny brown crumbs which must be woodlouse waste...so my cockpit must be their banqueting hall, parade ground and latrine. The boat is off the ground, so it would be tedious to crawl down the transom tubes and trailer-wheels in search of breakfast, then all the way back up later...

...they can only be eating the boat. There are odd bits of bare ply stiffening and iroko cleat backing-plates, which never get wet and so were never glassed-over or epoxied. But I thought woodlice favoured rotten wood - do I need to investigate the condition of the glassed-over wood ribs in the floor?

Has anybody had a boat damaged by woodlice before?
Click to expand...
They eat paper as well, so watch your charts.
 
Hydrozoan said:
The coprophagy has the benefit of recycling dietary copper, woodlouse blood (like that of marine crustaceans, at least one of which was their ancestor) being copper-based rather than iron-based.
Click to expand...
Collect the feaces and smear the outside of your hull with them. Really cheap environmentally friendly antifouling.
 
Hydrozoan said:
BTW, on the question of why some groups of animals have evolved to use hemocyanin with copper as the oxygen-binding metal.....

But I think we can rule out the woodlice nibbling Dan's prop for the copper.
Click to expand...

But.... it is a worry for boats coated with Coppercoat.
 
Sorry I'm a month late reviewing this...thank you all, for serious and non-serious contributions.

The boat's an open all-GRP Osprey dinghy so it's not likely that even several dozen woodlice making a full-time meal of the cockpit is indicative of imminent collapse, or so I choose to believe...

...but for several years, coming ashore after a long day on the water (or after capsize), I noticed the sound of water running through some internal cavity. I never located where, until a crack emerged in the 'buttressing' of the centreboard case. I drilled a 10mm hole in the lowest part of the 'rib' adjoining the buttress, and water poured out of it, when the boat was ashore. Not an alarming amount, but probably half a pint, so I assume the GRP-encapsulated 'rib' was flooded.

For a while I glassed-over the hole, believing I had mended the crack and sealed the rib-cavity. I imagined these ribs were balsa or foam structural 'formers' on which layers of glass were added to create structural stiffness, rather than requiring the weight of solid wood stiffening...but I don't know for sure. Certainly, the woodlice go into the hole, so it could be that they're busily scoffing the stiffening.

I don't know what's the best answer. I've ordered a syringe with a long pipe attached, so I can suck water from very hard-to-reach cavities. Then, if I may assume that I can get the space bone dry, I could flood the rib-cavity with thickened epoxy, both for structural stiffness and to exclude water and woodlice. But is a rib of thickened epoxy stiff/solid enough, without fibres in it for tensile strength?
 
zoidberg said:
They won't eat much.
It's the polyestermites one has to watch out for....
Click to expand...

OMG! Polyestermites? My yacht is made out of polyester: will they eat that?

Seriously I don't think we have "wood lice" in Australia. I googled and came up with

How do I get rid of Woodlice UK?
How to get rid of Woodlice. No treatment is necessary but if they persist put right any dampness, remove infested vegetation and use an insecticidal powder or long-lasting spray around door-thresholds or other points of entry. Amateur use products are available from your local garden centre or hardware store.Nov 28, 2017

Pest Advice for controlling Woodlice - BPCA
 
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