Tiny Bugs from Tiny Leaves

I’ve now finished uploading plant photos from last fall’s road trip through the western states.  If you’d like to help with identifying them, you can see them all organized by location here.  Thanks to those who have helped out already; I’ve been moving photos of confidently identified plants to the “Identified” folder, so the other folders should be getting emptier and emptier.

Now comes the fun part in my photo sorting: matching my photos of leaf mines to my photos of insects that emerged from them.  The plants from which I’ve reared adults are the ones I’m most interested in identifying, so that I can have complete data for specimen labels.  Unfortunately, there are a few specimens that I’ve already sent off to specialists without knowing what the host plant was, so I’ll devote a couple of blog posts to trying to rectify this situation.

Here’s a shrub that was growing in the coastal chaparral of Monterey County, California. The leaves were no more than 15 mm or so long.  Anyone recognize it?

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The small leaf size did not dissuade leafminers from living inside them.  Below is a leaf backlit to show the mine of a Stigmella species (Nepticulidae).

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As I’ve probably mentioned before, the family Nepticulidae includes the smallest moths in the world, and as it happens, the day before I found these mines, I got to see this moth when I stopped by the Bohart Museum of Entomology at UC Davis.  It was the smallest known moth at the time that article was written, but I was shown an even smaller one that had been found since then.  Both looked like specks of dust to the naked eye.

Anyway, like most nepticulid larvae, these emerged from the mines before pupating.  This one was about 2.7 mm long.

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In the rearing vial, the larvae spun whitish cocoons on the undersides of the leaves.  Most nepticulid cocoons I have seen have been a much darker brown.

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On December 2 I found this moth in the vial, unfortunately already dead.  It was 1.8 mm long.

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I sent the moth to Erik J. van Nieukerken in the Netherlands, along with two larvae for DNA barcoding.  On the same day I found the moth in the vial, I also found this parasitoid wasp, only 1.1 mm long:

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I sent the wasp to eulophid specialist Christer Hansson in Sweden.  He identified it as Chrysocharis wahli, which happens to be a species that he had named.  Given the shortage of microhymenopterists in the world, it is a very unusual thing to have the name of a parasitoid before I know the name of its host or even the host plant.  Chances are good that the moth doesn’t have a name yet anyway, but maybe someone out there has a name for the plant?

Added 10/14/2013: My tentative guess had been that the plant was some kind of Ceanothus, and several people have suggested this, but I am more convinced by the suggestion of Rhamnus crocea (redberry), or possibly R. ilicifolia (evergreen buckthorn). Everyone agrees that it is something in the buckthorn family (Rhamnaceae), making this the third time I have posted about a Stigmella species mining in a buckthorn: see also Rhamnus cathartica and Berchemia scandens.  Thanks to everyone who chimed in!

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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12 Responses to Tiny Bugs from Tiny Leaves

  1. I had no idea that moths of that size existed! Fascinating. I’m curious how you decide where to “hunt” while on these trips. Do you just pick a plant at random, knowing you’ll find something?

    • Good question! I’m pretty much continually scanning vegetation, and I’ve spent so much time consciously searching that I notice a lot of small and inconspicuous things when I’m not even looking for them (like when I’m hiking on a trail or even just going out to get the mail). I’ll see something out of the corner of my eye that clicks with one search image or another. But on top of that, every time I encounter a plant I haven’t seen before–particularly one with broad leaves that look suitable for leaf-mining–I spend some time inspecting it (including looking at the undersides of some leaves), and there is almost always something to find.

  2. Jen McDonald says:

    That moth has feathers. THAT MOTH HAS FEATHERS!!!! I shall name thee: Mord. Bith? Birth is just silly.

    The fungi I study are also notoriously difficult to find an ID for, almost always I have to resort to DNA identification in order to get something useful. The mushrooms I study are even sometimes 10 times bigger than your insects 🙂 I’m amazed at the identification ability (the ability to spot very, very subtle yet consistent changes in some aspect of morphology) of taxonomists in any field prior to the advent of DNA sequencing.

  3. My first thought was you had a type of Ceanothus, like Monterey (C. rigidus) or sandscrub (C. dentatus), but neither was a perfect match once I looked them up. So, my best guess is in the same family, the spiny redberry (Rhamnus crocea):
    http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=7075
    http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=41069
    http://calphotos.berkeley.edu/cgi-bin/img_query?rel-taxon=begins+with&where-taxon=Rhamnus+crocea
    I could be wrong, but hopefully this’ll get you down the right road.

    • Thanks! Ceanothus had been my original thought too, but there are so many species that I didn’t know where to start. Someone emailed me the suggestion of C. cuneatus, but that didn’t look right either. Rhamnus crocea looks like a very good match.

  4. Andrea Adams-Morden says:

    It is red berry,Rhamnus crocea or ilicifolia.

  5. I checked with my local expert on chaparral plants, who responded, “It’s Rhamnus crocea or ilicifolia.”

    http://en.wikipedia.org/wiki/Rhamnus_crocea
    http://en.wikipedia.org/wiki/Rhamnus_ilicifolia

    Hope that’s helpful.

  6. Kandis Gilmore left this comment on Google Plus:
    My friend Matt Guilliams says “For the plant, at first glance it looks like Rhamnus crocea, which is common in the area you describe. The leaves are spot-on, and the photo of the unopened flower looks like it will have four petals. You can check out photos of Rhamnus crocea here” : http://calphotos.berkeley.edu/cgi/img_query?stat=BROWSE&query_src=photos_flora_sci&where-genre=Plant&where-taxon=Rhamnus+crocea&title_tag=Rhamnus+crocea

  7. Pingback: Using Bugs to Identify Plants | BugTracks

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