Thin Moth – Bedellia? Or Gracillariidae?

2010 March 20

Sam spotted this insect on the side of the house on March 14, while we were out getting pictures “in the field” with the new camera[1]. It was about the size (about 1 mm wide and maybe 6 or 7 mm long) and shape of a grass seed stuck to the wall, which is probably what it was pretending to be. In fact, until I looked at it through the camera viewfinder (which gave quite a bit of magnification), I couldn’t quite be sure that it wasn’t a grass seed.

(I was handholding the camera, and I need more practice to hold the focus properly without a solid support, but I guess these are OK for a first try. Also, the camera viewfinder has a diopter adjustment to correct my vision, and it might not be set quite perfectly for my eye)

It sat very stationary, occasionally flicking its very long antennae forward.

Eventually, though, after I’d taken a bunch of pictures, it abruptly popped its wings open and flew off, very fast, and that was the last I saw of it.

We thought for a very brief period that it might be some kind of stick insect, but as near as I can tell it is a moth. My guess was that it was one in the genus Bedellia, although as Dave points out in the comments below, the pose and body shape look rather a lot like the members of the family Gracillariidae.

The only member of the Bedellia genus that I can find much information about is Bedellia somnulentella, whose caterpillar is a leaf-miner that is a serious pest of sweet potatos and morning glories. (Incidentally, did you know that sweet potatos are a type of morning glory? Me neither.) Dave suggests it is a relative of the Ash Leaf-Roller, Caloptilia fraxinella (although probably not that specific species, because the patterning on the wings is somewhat different). These overwinter as adults, frequently around houses, and are commonly seen very early in the spring on house siding, just like this one was.

In any case, the caterpillar is most likely some sort of leaf-miner (although some of them only mine within the leaf when they are very small, and graduate to leaf-rolling when they get bigger). It really is helpful to know the whole life history to get a good ID on insects in general. A lot of insect species (particularly micromoths such as this one, and parasitic wasps that lay eggs in particular other insects), have adults that are either variable or look a lot like other species, and have to be told apart based on what the larvae eat. A lot of others have generalist larvae that eat most anything and all look a lot alike, and so you need to get the adults to find distinguishing features. And then, of course, there are the ones like rove beetles where both the adults and larvae are generalist feeders and lack diagnostic features, so that even the experts have to throw up their hands and call it a day. Which sometimes makes me wonder – how do some of these species ever get described and named in the first place?

[1] I’ve been saving up for a new bug-photographing camera for a while, because a good digital SLR has a lot of features that make it more useful for macrophotography than a standard point-and-shoot camera. Then in November, I was looking over the KEH Camera Brokers website[2], and realized that I could get a used Canon 10D SLR body for $240. This is about the price of a new point-and-shoot. For reference, the Canon 10D was a $2000 camera as recently as 2004. It was one of Canon’s second generation of digital SLRs that had resolution as good as the resolution of film, and it has the two features that I really wanted in a camera: (1) the ability to take interchangeable lenses, and (2) when you press the shutter button, it takes the picture now, not 3 seconds from now (after the bug has flown away or run off).

Of course, this was just the camera body, it didn’t come with a lens, macro or otherwise. I first tried using the lens from my old SLR camera, mounted backwards to give high magnification. This is a standard trick for getting high magnification without a dedicated macro lens. It sort of worked, but I found out that it had a lot of aberration and distortion everywhere except right in the middle of the field of view. I think this was a result of the aperature diaphragm no longer being in the right place to do any good when the lens was backwards. As a result, the images came out not so good. So, it was looking like I would need to get an actual dedicated macro lens.

Right about this point, Sandy decided to do something very nice for me, and bought me a Canon 100mm Macro F/2.8 lens as a Christmas present. This is a very nice, very versatile lens: at closest focus, it can give 1:1 magnification, but it can also work as a portrait lens and a mild telephoto lens, so I can go from taking pictures of bugs to taking pictures of children to taking pictures of birds at a moment’s notice.[3]

One nice feature is that this lens does not block the flash on the camera, so I can actually use the flash at high magnifications. This means I can hand-hold the camera, and take shots out in the field of insects in their natural habitats! At the moment, I’m just using the built-in pop-up flash, but I’ll probably want improved flash capability sometime in the future.

And, when I want really high magnification, I can still take my old Olympus lens, reverse it, and put it on the end of the Canon lens to look at tiny bugs that are less than a millimeter across! That requires using the microscope stand for a support, though.

One feature that it doesn’t have, and that I really miss, is the manual focusing aids that my old SLR had – a split-image focusing screen with a microprism ring. This was a device where, if the image was not in focus, there was a line across the image where features running across the screen did not line up, and a halo of blurriness due to the microprisms. When it was perfectly in focus, the image features would line up and the microprism blur would vanish. The modern digital SLRs have abandoned that, depending on autofocus. Which would be OK, except that autofocus doesn’t work very well in macrophotography, so I have to focus manually. Without the manual focusing aids. Boo! If there’s some way to retrofit an old-style manual focusing screen into a Canon 10D, I’m all ears.

[2] I’d had previous good experience buying used equipment from KEH. I’d bought my old film SLR camera (an Olympus OM-2) from them back in 1988. Even though it had been used, it worked perfectly for me for almost 15 years, before I stopped using it due to the difficulty of finding someplace competent to develop the film. So, I had reason to trust KEH to provide a quality product. I figure that anything that they grade as “EX+” is nearly as good as new. And, the fact that they’ve been around for decades meant that I wasn’t dealing with some fly-by-night outfit, or with some individual on Ebay who I might have no inherent reason to trust.

[3] And thus I begin down the trail to my doom that Alex Wild warns us about. The next thing will probably be to try to find a reasonably-priced MT-24 EX Twin Flash, maybe I’ll be able to turn one up used. Eventually, I’ll probably end up getting a Canon MP-E 65 mm 1-5X Macro lens, and then my doom will be complete. Although, I’m thinking that maybe I should just rent one for a couple of weeks, take a few thousand pictures of tiny bugs in the yard to build up a backlog, and then send it back. Thereby saving myself about $800.

4 Responses
  1. March 21, 2010

    Turning the lens around? I never would have thought of that. Way cool.

    As for the moth, it made me wonder if any enterprising aerospace engineering grad students had ever studied the aerodynamics of moths as a function of body type. This skinny, little dude ought to fly quite differently than the chubby ones I’m used to seeing.

  2. March 22, 2010

    I’d just like to note that there are two distinct ways of turning the lens around to shoot through it backwards: (1) working with only one lens, you can use a reversing ring to screw a mount for your particular make of camera into the filter threads on the lens. (2) working with two lenses, you can use a macro coupling ring to put a reversed lens in front of your normal lens. There are a few places where you can get either of these. I got mine from Adorama Camera, who seem to have an unusually good selection of this type of adaptor.

    I personally have gotten better results using a macro coupler and two lenses, than using a reversing ring and a single lens.

    And this moth was pretty fast compared to larger moths, flying more like a fly. If it was what I think it was, its hindwings were probably a lot like the bushy, featherlike things shown on this page

  3. March 27, 2010

    The little moth does look like a leaf mining microlep, but may be a member of the Gracillariidae, aka Leaf-blotch miners. In Edmonton, not too far to your north and west, adults of the euphoniously named Caloptilia fraxinella overwinter around houses and have just that pose and upturned bit at the end (but are more grey and patterned that your specimen). Their larvae fold and mine the leaves of the boulevard green ash and make quite a mess in the summer. I couldn’t find anything that looked a good match for your photos – but few people notice these tiny moths and fewer still take such nice pictures.

  4. March 27, 2010

    Thanks, Dave, it does look a bit more like those than the ones I thought it was. In particular, the smooth head is a pretty close match.

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