Indian Meal Moth

2007 April 21

This week, we have another one that can be positively identified down to the species. It is an Indian Meal Moth, Plodia interpunctella. These are commonly referred to as a “pantry pest”, and we found this one (surprise, surprise!) in the pantry. They came in to the house originally in some infested birdseed from WalMart, and they’ve been around at a low level ever since. They feed on dry grains, flour, and similar materials.

There are two photos here, because of focusing issues with my setup for small items. The first one has the head in focus, while the second is focused on the trailing edge of the wings.



The reason I didn’t get the whole moth in sharp focus is that they rest with their heads elevated and the trailing edge of their wings pressed against the surface they are resting on. It looks to me like they do this to mimic a bud on a branch. The lens I am using for close photography has a very shallow depth of field, and so the slight difference in elevation between head and tail meant that it didn’t focus evenly on the whole moth.

For very small insects, I am using a conventional lens from my old single-lens reflex camera, mounted on the digital camera so that I am looking through the lens backwards. This is a standard trick for making a macro lens on the cheap. You can buy male-male threaded adapters that screw into the filter ring on the reversed lens, so that it can then be screwed onto a normally-mounted lens. It actually works pretty decent, considering the kludged-together aspects of it. However, it has pretty limited focus travel, and the depth of field is only a couple of millimeters, so I had to mount the camera on a tabletop tripod and get everything within about a centimeter or so of the correct distance from the lens in order to get the subject in sharp focus. If I can find a focuser rack from an old microscope that I can salvage, that might be even better than the tripod, which even though it is only 6 inches tall is still about twice as tall as it should be. There are better ways to do this, but it looks like they all entail spending several hundred dollars, which I am not prepared to do at this point.

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