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Unidentified Leaf Miner - Manzanita (Arctostaphylos) sp. - Marmara on-arctostaphylos

Unidentified Leaf Miner - Manzanita (Arctostaphylos) sp. - Marmara on-arctostaphylos
Woodside, San Mateo County, California, USA
February 2, 2008
Found this striking leaf mining pattern on a Manzanita leaf. Any tips on lists of Manzanita leaf miners would be appreciated...

Images of this individual: tag all
Unidentified Leaf Miner - Manzanita (Arctostaphylos) sp. - Marmara on-arctostaphylos Unidentified Leaf Miner - Manzanita (Arctostaphylos) sp. - Marmara on-arctostaphylos Unidentified Leaf Miner - Manzanita (Arctostaphylos) sp. - Marmara on-arctostaphylos

Moved from Marmara arbutiella.

Although mines on manzanita have been attributed to Marmara arbutiella, according to David Wagner the manzanita feeder is a different species, consistently smaller than M. arbutiella.

Moved from leaf mines. I found the problem: this isn't manzanita, it's madrone! Right? I just read a description of the mines of Marmara arbutiella that matches your image perfectly:

"Mines made by these larvae are very characteristic in appearance, for with their cell-shearing mandibles they sever the cuticle of the leaf from its parenchyma so adroitly that the colorless epidermis is left almost "chemically clean." The mine, therefore, appears by reflected light to be a solid white line... The galleries increase in width very very slowly but in length they increase rapidly, and wind about crossing and recrossing until they involve much of the upper surface."

If you see these again, look for mines on the twigs as well--the larvae can move freely between the twigs and leaves, which is unusual for a leaf miner.

Madrone and manzanita
have a very similar appearance with their smooth bark that sheds older layers and the smooth, fairly thick leaves. I wouldn't be surprised if they were closely related.

Okay, I just looked them up. Madrone (Arbutus menziesii) and Manzanita (Arctostaphylos) are both members of the Heath family (Ericaceae) that also contains Salal (Gaultheria) and Huckleberry (Vaccinium). Salal has a similar leaf as I recall and might also be a suitable host plant.

Well -
it's been a long time, but I really thought it was Manzanita at the time... I will look for some more of these mines...

You're probably right--
I just checked here and "Arctostaphylos sp." is listed as a host plant for this species in addition to madrone. Certainly don't take my word for it on western plant IDs, but I feel good about the moth ID.

Although lacking size reference, the leaf in this image looks "small" to me, perhaps only few centimeters long? Manzanitas (Arctostaphylos) leaves are generally small. The break used in The Flora of the Pacific Northwest (where they separate in the last couplet for the Ericaceae key) is "less than 7 cm"). Madrone (Arbutus menziesii) leaves are large ("greater than 7 cm"), in the range of 7-15 cm long.

Confused -
yes, this was identified as a Manzanita.

Sorry for any confusion, I thought there was a lingering uncertainty about the exact ID, so I just wanted to add that it appeared to me to be manzanita (my only caveat being that I did not know the dimensions of the leaf). Happy holidays! :)

Got it -
thanks. I should have included the dimensions of the leaf - sorry about that - it was indeed rather small, as I remember. Happy holidays to you as well. :)

Cool -
thanks for all your work on this one. Will definitely look for more of these mines.

Manzanita leaf miner
I've only been able to come up with one leaf-mining species, Phyllonorycter manzanita, from this database, among other sources--but mines in that genus should look something like the ones on this page--although I haven't found anything to specifically confirm that the mines of this species look like all the other mines in this genus. Definitely worth trying to rear these if you find them again!

Thanks, Charley!
Yeah - I will give it another try if I find them again - we have lots of manzanita out here! :)

I wonder
if you could rear them by keeping a manzanita sprig in water with some fine mesh secured around it.

Or maybe
you could put a mesh bag or stocking over a branch and secure the opening with tape, then check it every day or so?

Thanks for both of your comments...
this leaf was on a shrub that is a half-hour from my home, so wrapping a branch "in situ" and checking it daily wouldn't work. Jim's idea might work better in this case if I had thought of taking a sprig instead of just this one leaf... darn.

More generally, I guess I was fooled into thinking that this was evidence of past arthropod activity and not that there were bugs currently in this leaf - do you both then think that there are small immatures in this leaf? Is there any way to tell now?

If the larva is still at home,
it would be at the end of the tunnel. I would tease the leaf apart with a fine scalpel tip and look it over carefully with a hand loupe.

Thanks for the advice.
I just added two photos of the larva I found...

Well, well!
Was it alive? Maybe someone will recognize it despite the poor detail (I know, 1mm...). I'm afraid I can't even tell you which order it's in. Still, it's nice to have found it.

Thanks, Jim
nope - it was dead and a bit dried up to boot - I should have opened up the tunnel immediately on getting it home and/or tried to keep the twig alive with some water... Next time...

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