Indian Meal Moth

2013 November 30

Sandy spotted this tiny moth (about a quarter-inch long) fluttering around the house on March 17, 2013. There aren’t a lot of insects active around here in March, so I had to take pictures.

This is probably an Indian Meal Moth, Plodia interpunctella, which is a pretty safe bet any time you find a small, bicolored moth indoors. Particularly if you find it at a time of year that moths generally aren’t flying.

This one was in a somewhat uncharacteristic pose, with its wings slightly spread to expose the light-gray, heavily-fringed hindwings.

The last time I photographed one, way back in 2007, it was in a more typical pose, with the wings tightly furled over the back.

Indian Meal Moths got their name because they were commonly found infesting ground corn, which was widely known as “Indian Meal” back in the mid-1800s. They are currently found around the world, infesting all sorts of stored dry grain products, particularly flour, grain meal, and baked goods like crackers. The caterpillars spin webbing over the top of the grain that they are eating, so they are pretty distinctive.

Bugguide says they were originally a South American species, that has found our pantries to be a more congenial environment. Given that they don’t have any difficulty with drying out even though they are eating dry grains, I kind of suspect that they are from one of the more arid parts of South America. Getting rid of them isn’t difficult in concept, you just need to keep all grain products in tightly-sealed containers so that the adult moths can’t get in to lay eggs. The moths are pretty tiny, though, so it does have to be a tight seal. Just folding over the top of a paper flour sack isn’t going to be sufficient.

Aside from the webbing and their droppings, they don’t actually do much to the nutritional quality of the food they are eating. So if you have a container that is only lightly infested you can just skim off the webbing part (which will remove most of the caterpillars, their frass, and their shed skins), and freeze the rest to make sure to kill off any eggs. Just be sure to have a tight container to put it into afterwards, or bake with it right away.

“But what if I miss some?” I hear some of you cry. Well, the caterpillars aren’t very large, and they will bake into your muffins just fine. You’ll probably never notice them[1].

[1] Besides, it’s not like you don’t already have insect parts in the flour, anyway. The FDA allows a significant amount of insect contamination in food before they will do anything about it. And one of my memories of my childhood on the farm was when I looked into the grain wagon just after the combine had filled it up with wheat, and the “wheat” was at least 20% insects (mostly grasshoppers, lady beetles, and stink bugs). Most of the insects subsequently get removed when the grain is screened and winnowed at the grain elevator, but still, the ones that are about the size and weight of a grain of wheat probably stay in there.

Incidentally, this suggests that one could modify a combine into an insect-harvesting machine. It could just run over a meadow, essentially vacuuming up the insects, and collect them in ton lots. If anybody actually wanted insects by the ton, it would be quite practical to run a free-range “insect ranch”. The only tricky part would be then sorting them into specific kinds of insects – if you want grasshoppers to fry up, you probably don’t want a lot of stink bugs mixed in with them.

One Response
  1. Katbird permalink
    December 2, 2013

    I recently had some come in raw peanuts I had bought for the squirrels. I should have frozen them. All my birds seed is kept in garbage cans in the garage and my flour is in the refrigerator. I got rid of the pests that the kids always called “birdseed bugs” in about a week- killing caterpillars that had made tunnel in the seam between the ceiling and wall and swatting about 10 fliers (sorry- they had to go). I have not seen any now for 2 weeks and am holding my breath. Freezing bird seed seems to help keep these down. I will say when the males are displaying they can be quite attractive.

Comments are closed.