A prolific poster of leaf mine observations wrote to me today to make sure he wasn't overwhelming me with an excessive number of observations, and I thought it might be useful to share my reply with everyone.

It is true that I'm still two months (and about 3800 observations) behind in reviewing observations in this project after my summer travels, but I certainly wouldn't want to rein in anyone's enthusiasm for leafminers! If you do your best to ID each observation, it isn't really too much work for me when I just get to click "agree" on most of them. And when you have no clue, the AI/CV is getting better and better--when I was new to iNat I used to get grumpy about people suggesting ridiculous IDs based on what the computer suggested, but the real problem is people who go around agreeing with ridiculous IDs when they actually have no clue. At this point, if you select the computer's top suggestion when you don't know what a leaf mine is, I think you'll be right more often than not, and if the ID is wrong, it's not any more work for me to add the right ID than it is if you just put the default "Pterygota."

And just to make sure you're aware, the first edition of my leafminer guide is available for $5, and that should help a lot with identifications when you know what the host plant is: https://bugtracks.wordpress.com/2021/06/25/leafminers-for-all/

I'll add that if you want the most current and complete information about North American leafminers, I recently started sending out monthly installments of the third edition, as I announced on my blog earlier this month: https://bugtracks.wordpress.com/2023/11/02/announcements-3/. The second and third editions include a spreadsheet of 1000+ mystery mines that need further investigation, for those of you who are interested in collecting and rearing leafminers to try and solve some of these mysteries.

Thanks everyone for your interest in leaf mines, whether you only occasionally photograph them or post dozens of observations a day!

Charley

Hi everybody,

I've managed to keep up with this project through the end of June, but I will have very limited computer access between now and mid-August, so there is no point in tagging me on anything until then. It also (as always) will help me tremendously in trying to catch up on the backlog if people make an effort to ID observations (their own or others') before I get to them--it's really helpful to just be able to click "agree"! If you want to try identifying leafminers but don't know how to go about it, you can get my e-book here.

If you have something urgent you want to reach me about--like rearing advice (beyond what's on my website) or questions about what to do with specimens you've managed to rear--the best way to reach me is by email; I'll also check iNaturalist messages when I can.

Thanks, and I look forward to seeing what you all find this summer!

Charley

This is a friendly reminder to not post observations of holes in leaves to this project, unless of course they are associated with leaf mines. And please take a look at this blog post before identifying anything as Japanagromyza viridula (oak shothole leafminer), whether in this project or not.

I just put together a blog post explaining this, in case anyone's interested: https://bugtracks.wordpress.com/2022/11/13/can-gall-midges-be-leafminers/

Here's a mystery I've been trying to solve for a decade now: a long, linear leaf mine of an agromyzid fly on Adenocaulon bicolor in the Pacific Northwest. It should be a relatively easy one to rear, since the puparium is formed in the leaf (hidden on the lower surface) and there are apparently at least two generations per year, with mines present from June to October.

@jmole, WA, 6/9/2021

@lumenal, OR, 7/6/2021

@lumenal, OR, 7/12/2022

@lumenal, OR, 7/18/2022

@flammulated, OR, 7/22/2021

@flammulated, OR, 7/30/2021

@brnhn, WA, 8/18/2022

@kurtsteinbach, WA, 8/30/2021

@brnhn, OR, 9/5/2021

@johndreynolds, BC, 9/18/2020

Here's another one I'm really hoping someone can collect and rear. The South African moth Digitivalva delaireae is being considered as a potential biological control agent for Cape-ivy in California and Oregon, but meanwhile people have been regularly observing some native(?) leafminer on this plant, and no one knows what it is. There is typically a roughly circular brown spot at the beginning, where the mine is apparently contorted or forms a tight spiral, and this suggests to me that the fly is something other than just one of the polyphagous Liriomyza species that are common in southern California. Although mines have been observed in just about every month of the year, the only one with a larva inside was found on April 11 in Marin County.

@thetorterra, Santa Cruz Co., 1/16/2022

@manidae, Los Angeles Co., 3/28/2020

@marionanoiram, Marin Co., 4/11/2016 [larva present]

@nealkelso, San Francisco Co., 4/24/2021

@garth_harwood, San Mateo Co., 6/4/2020

@sea-kangaroo & @leslie_flint, San Mateo Co., 6/16/2019

@silversea_starsong, Orange Co., 7/4/2021

@ctrubo, Los Angeles Co., 7/18/2022

@cynestor, Santa Barbara Co., 7/23/2022

@dlbowls, San Luis Obispo Co., 8/9/2021

@cynestor, Ventura Co., 8/27/2022

@esppim, San Francisco Co., 8/31/2021

@sea-kangaroo, Monterey Co., 9/18/2021

@danieldas, San Francisco Co., 9/19/2021

@gyrrlfalcon, San Mateo Co., 10/16/2019

@conormcmahon, Santa Barbara Co., 10/18/2021

@bugornot, Orange Co., 11/2/2020

@nealkelso, San Francisco Co., 11/8/2020

@nealkelso, San Francisco Co., 11/16/2020

@nealkelso, San Francisco Co., 11/17/2021

@wxynez, Los Angeles Co., 12/1/2021

@thetorterra, Santa Cruz Co., 12/6/2021

@jon_sullivan, Monterey Co., 12/30/2018

Another commonly observed mystery leafminer that I'm hoping someone can collect and rear: An Ophiomyia species (Agromyzidae) that forms winding linear mines on Lantana camara, L. x hybrida, and maybe other Lantana spp., in California, Texas, Mississippi, Alabama, and Florida. The well-known species O. camarae makes a mine based on the midrib, with short extensions into the blade along either side:
@silversea_starsong, Mission, TX, 11/5/2021
The mystery mines are not based on the midrib, although they sometimes have similar short branches where they encounter lateral veins. It's conceivable that they are made by the same species, but adults need to be reared to confirm this.
@susanhewitt, Carlsbad, CA, 10/1/2019
@dan_johnson, Houston, TX, 10/6/2019
@kimberlietx, Southlake, TX, 6/16/2020 (note long lower-surface portion in this example)
@victorengel, Austin, TX, 7/2/2020
@silversea_starsong, Newport Beach, CA, 7/15/2020 (another example with a long lower-surface portion)
@silversea_starsong, Garden Grove, CA, 10/26/2020
@wsweet321, Long Beach, CA, 11/1/2020
@terit, Natchez, MS, 11/15/2020
@wsweet321, Long Beach, CA, 1/24/2021
@sessilefielder, Los Angeles Co., CA, 1/2021
@chalon9, El Cajon, CA, 7/23/2021
@joemdo, Medley, FL, 7/26/2021 (this one has a distinct frass line and may have been made by a different species)
@silversea_starsong, Orange, CA, 8/23/2021 (the first example follows the lateral veins a lot)
@biocowboy, Long Beach, CA, 8/24/2021
@wsweet321, Long Beach, CA, 9/16/2021
@milliebasden, San Diego, CA, 9/28/2021
@vcharny, Dauphin Island, AL, 10/11/2021
@silversea_starsong, Mission, TX, 11/5/2021
@sessilefielder, Los Angeles, CA, 3/13/2022

This is the first in what I expect to be a series of posts highlighting commonly observed mystery leaf mines. My hope is that people will keep an eye out for them and collect any occupied ones so that adult insects can be reared and we can put names to them. You can click on any of the images below to get to the original observations. These are all mines of some unknown agromyzid fly on Pacific hound's tongue (Adelinia grande); they have been found in several California counties. Empty mines have been found as early as March 9; no one has yet found ones that clearly have larvae inside, although some photos taken in late May show small and fresh-looking mines, so there may be two generations per year.

@sea-kangaroo, San Mateo Co., CA, 3/9/2018, 5/29/2019, 6/10/2020


@temminicki, San Mateo Co., CA, 3/11/2018


@merav, Santa Clara Co., CA, 3/14/2021


@debkccb, San Mateo Co., CA, 3/15/2020


@u_phantasticus, San Mateo Co., CA, 3/20/2020


@chloe_and_trevor, Marin Co., CA, 3/31/2021, 4/22/2021


@cmaci, San Mateo Co., CA, 4/4/2020


@zufi, San Mateo Co., CA, 4/9/2021


@selwynq, San Mateo Co., CA, 4/11/2021


@elonicera, Santa Clara Co., CA, 4/14/2021


@melanopygus, Marin Co., CA, 4/29/2018


@leslie_flint, San Mateo Co., CA, 4/30/2021, 5/4/2020


@gyrrlfalcon, San Mateo Co., CA, 4/16/2021, 5/4/2020, 6/5/2020


@leptonia, Santa Cruz Co., CA, 5/10/2017


@owicki, Santa Clara Co., CA, 5/11/2020


@kzias, San Mateo Co., CA, 5/24/2020


@hoechsle, Santa Cruz Co., CA, 5/30/2019


@calloohcallay, San Mateo Co., CA, 5/30/2020


Update, 3/11/2022: People have found some occupied mines in 2022!


@gina-barton, Santa Clara Co., CA, 3/5/2022


Having seen this puparium that @nancyasquith got from one of these mines (Santa Clara Co., CA, 3/10/2022), I'm now reasonably sure this is an Agromyza species.

Hi everyone,

In the interest of making leafminer identification more accessible, you can now get the first edition of the Leafminers of North America e-book for as little as $5 US. For details, see today's BugTracks post.

Charley

On Thursday evenings from April 29 to May 27 I'll be offering a "Leaf & Stem Mining Insects of the Southern USA" online seminar. "Southern" is anywhere that spring is far enough along for there to be plenty of leaf mines to observe! Details here.