Monday, November 12, 2007

Don't coddle the codling moth

11/25/07: edited post briefly to correct spelling and fix a typo.

Last time I wrote about how to use wormy pears, because I've been too lazy to control the codling moths whose larvae infest my fruit. This morning I read a useful article in Gardens West (a great Canadian gardening magazine that I recommend highly) on how to control codling moths. The article isn't online, unfortunately, but you can buy the issue (October 2007) from their site for $3.18 CAN (about $3.29). I'll include the main points here, but if you want their instructions for making your own coddling moth trap, please buy the issue.

The article includes background on the codling moth life cycle and the damage they do. The codling moth pupates over the winter, then emerges in spring to mate. Females lay their eggs on your fruit tree, sometimes on the fruit itself. When the larvae hatch, they eat their way through your immature apple or pear to feed on the seeds at the core. They leave behind the ever-attractive brown trail made of larva frass.

Brief, immature aside: Have you ever noticed all the clever, academic-sounding terms we have for... um... poop? I hadn't heard "frass" till I read this article (according to, it means "insect excrement"), but now I think I'll throw it around in casual conversation.

Husband: "How was your day?"
Me: "Frassy!"

OK, maybe not.

Back to our entomology lesson... After the larva has feasted on your apple seeds, it emerges to look for a good place to pupate. According to the article,
A safe spot can include cracks or grooves inthe bark of the tree (or any other piece of nearby wood), leaf litter or even just in the soil (pretty much anywhere protected from the ravages of winter weather or predators).
Codling moths are hard to control with insecticides, because the larva is sheltered inside your formerly-appetizing fruit all season. So, according to the article, we have to try different methods:
  1. Constant vigilance and hygiene: Check your developing fruit and destroy any that show moth damage. Other articles I've read emphasize cleaning up around your trees in the fall to get rid of leaf litter and other places the moths can pupate.
  2. Traps: You can buy pheromone traps that will lure horny male moths inside. This gives a whole new meaning to that line from the old Roach Motel commercials: Moths check in, but they don't check out. It's basically a fake no-tell motel for moths. The article includes instructions for making another kind of trap that provides an attractive food source as bait. Those work for both males and females (and there has to be a joke there somewhere, but I'm not going to look for it).
  3. Pheromone distractions -- bits of plastic impregnated with pheromones, intended to confuse the male moths so they can't find the real females. (And yeah, there's probably a joke there too, but I'll spare you).
  4. Trunk banding -- wrap the tree trunk in corrugated cardboard (for exact instructions, see the article) to create an attractive place for the moths to pupate. Once they're tucked away for their winter sleep/metamorphosis, remove and destroy the cardboard. Yes, you too can be the Freddy Krueger of the insect community.
I guess I don't have any more excuses for having frass-contaminated fruit. Since I'm way too lazy for constant vigilance, I think I'll try the pheromone traps and homemade food traps. Mwaaahaaahaaaaa...

1 comment:

Anonymous said...

You can also bag your tiny apples with paper bags so that the larvae can't get to them.