Wednesday, 21 February 2007

Caterpillars on the march

The Indian meal moth caterpillars* (Plodia interpunctella) are emerging from the remnants of cereal in the pantry to search for pupation sites. So far, all the ones I've seen have been heading upwards. Those that I don't manage to intercept get as far as the cornice and stop, perplexed. Left or right? I'm torn between eradicating the little bastards as soon as I see them and letting them get to the cornices so I can record their directional preferences.

The caterpillars produce a spacing pheromone when feeding, which keeps them at arm's length ... proleg's length ... apart from each. Presumably this prevents over-crowding. (Although it doesn't seem to be working in my pantry.) Unfortunately for them, parasitoid wasps can detect the pheromone and track down the caterpillars for use as living incubators. The killers aren't doing their job because these individuals are plump—and not because they're packed with wasp larvae. The one on the left got fat on dried pawpaw.

*Judging by their numbers, I must be supporting the entire moth population of western Melbourne.


Duncan said...

You should be collecting them and feeding them to Blue Wrens somewhere. ;-)

Snail said...

I'll do that, Duncan. I've been offering them to spiders but they don't seem keen.

Anonymous said...

man i got these things all through my pantry like thousands of them. and they are all over the roof n shit.