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Leaf mines on Ceanothus oliganthus - Xenolechia ceanothiella

Leaf mines on Ceanothus oliganthus - Xenolechia ceanothiella
Bulldog Lateral Trail, Malibu Creek State Park, Los Angeles County, California, USA
November 22, 2015
Lots of these mines on a single Ceanothus oliganthus plant. As it happens this was the only bush of Ceanothus oliganthus I could find in this area.

The mines shared the same characteristics, with obvious branching from a single trail.

Moved from Unidentified Leaf Mines.

I agree with Terry (and C. oliganthus is one of the recorded hosts for this moth). If you flip the leaf over, there should be a short tube of silk outside the entrance of the mine, which the larva uses as a retreat. I once collected mines like this in Oregon in October, and the larvae were still alive the following April, but I didn't manage to rear any. So it isn't too late to find occupied mines.

Lee, Hodges and Brown (2009) placed this species in Xenolechia--I'm not sure why MPG doesn't reflect that. I also read somewhere (maybe in the recent paper describing Xenolechia ceanothiae Priest?) that Recurvaria consimilis and R. francisca (likewise on Ceanothus) are misplaced in Recurvaria, but for whatever reason no one has done anything about moving them to another genus.

Mine entrance?
Where would that be Charley? I'm not sure how, but to this day I still have not seen a larva of any leaf or stem-mining species. I've even taken the leaves home to look at under light and under close magnification. Everything seems to be empty.

In this species,
the mine entrance would be on the lower leaf surface, adjacent to the midrib or a major vein. In this particular example the part of the mine adjacent to the entrance is conspicuously dark reddish, right along the midrib, and between that and the petiole there seems to be a buckling of the green part of the leaf corresponding with the silk retreat on the lower surface. In this species the larva would be difficult to spot, as it would likely hide in the purplish area or in the silk retreat when disturbed. You could determine if it was occupied by putting the leaf in a vial and waiting a day to see if there is any frass accumulation in the bottom of the vial (because the larva of this species expels its frass).

Many leaf mines are less conspicuous when they are occupied, so you may need to adjust your search image if you want to find larvae. If you see bright whitish mines, for instance, look nearby on the same host plant for some that are smaller and still greenish. Phenology is also important--if all the mines of a given type seem to be empty, you may need to come back to the same spot earlier in the season the following year. The evidence of leafminers sticks around much longer than do the larvae themselves.

Moved from ID Request.

Recurvaria ceanothiella?
These *might* be early-stage mines of Recurvaria ceanothiella (Gelechiidae), which was described from specimens reared from Ceanothus in California. These mines match Braun's description of early damage by R. ceanothiella and resemble early-stage mines of the related eastern-USA species, Recurvaria consimilis, as seen in the upper left-hand panel of the photo posted here.

Thanks Terry
Several leaves were far more significantly damaged than this, to the extent that a large complete area of the leaf was mined out. This pattern of progression is pretty much identical to that image you have linked.

So this seems like a good suggestion indeed. There was only one Ceanothus oliganthus plant in this entire area, and I did not see mines on any other Ceanothus species.

I was hoping to see lepidopteran larvae in these but I could not detect any at the time.

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