The Moth Trap

A while ago I kept seeing weird little brown insects flying around. They didn’t really bother me, and the cat had fun catching them, so I let them be for a while. When I found a dead one on the floor one day I decided to see if I could figure out what it was. With the dead bug on my desk I searched several insect websites and typed random descriptions of it in Google. It took me about thirty minutes to figure out that it was not a type of fly, and another twenty to match it up perfectly with a description of a webbing clothes moth.

Oh no, they are secretly eating my clothes! Suddenly they were bothering me, and I wanted them out!

I knew that moth balls would definitely kill them. They contain naphthalene or paradichlorobenzene — enough to do in any moth. But they smell, and they can be toxic to non-moths as well. Now, I wasn’t planning on sniffing moth balls, but my cat would love those little toys, and she also eats any dead moth she finds. No moth balls in my house, that was the plan.

Alternatives to moth balls are cedar wood and pheromone traps. I bought some cedar to put in the box with winter sweaters, and bought a pheromone trap at Grassroots.

This trap is a cardboard house with glue on the inside, and a pheromone lure in the middle. The lure attracts male moths, and the idea is that they get trapped and this will eventually stop them from breeding.

The pheromone trap works. It’s trapping moths. But since April I only trapped 10 moths. There are bursts of activity, in which I catch a few in a row, and quiet times in between. The lure is still working, because one of them flew in quite recently.

What worries me is that moths lay 100-300 eggs, and I only caught 10. On top of that, I’m catching adults, while the larvae are the ones that do the damage, and they might still be around. I don’t know where they are! My clothes look fine. They might be in a rug or a curtain. Who knows!

Even more worrying is this paper that says that male moths are more attracted by pheromones from a nest than by female sex pheromones. I think the lure has sex pheromones, not nest pheromones. A lot of moths hang around in the bathroom. Is that where the nest is? There is less fabric there than anywhere else in the house, so it seems stupid to me, but then again, so does flying into a house with glued walls just because a little lure smells like female moth.

Getting more cedar chips is the next course of action, but cedar works by making male moths unable to smell pheromones, and that might interfere with the moth trap! So the cedar should be close to my clothes or where I suspect the nest is (in the bathroom?), but not close to the trap.

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Taxonomy, chemistry, biology, scientific literature, experimental setup… All this for a common household problem, and nothing I did was particularly geeky (except maybe identifying the insect and looking at scientific literature to read about moth pheromones.) I could write a thesis on this. Or at least a proper lab report, with goal, hypothesis, methods, conclusion, discussion, references, and suggestions for further experiments. Actually, I did that just now – see it?

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