CaliFlowers said:

I think if you're going to strip leaves in order to control leafminer, it might be best done in the late fall, after the larvae have pupated for the winter, the

I think that would work if the insect had only one generation a year, but unfortunately it can have several. So if you don't pick the infested leaves when you see them, and allow the earlier ones to survive, then they'll keep the cycle repeating. Each leaf with larva that you remove and destroy is one less adult to reproduce. You may actually be able to squash the larva inside the leaf so that the leaf can stay on - something that might be worth a try anyway.

I know they have more than one generation for the growing season, but I read somewhere that they all overwinter as pupa. Once they're in that state, (late fall, early winter?) a complete leaf removal should get the majority of them. By then, the dormants have dropped their leaves, and I imagine that the evergreens aren't really going to miss theirs. The pupae I found were so far down in the fans, at the base of the leaves, that you'd have to rip the leaves off in order to locate and squish 'em.

I guess you could also wait for the February Flush and do it then—that way the evergreens could benefit from the protection of their leaves over winter. Might be better that way.

I was suggesting squishing the larva while it is mining and before it gets far down the leaf, not the pupa because, as you say, they are too low down. Multiple generations a year means that each generation is pupating and emerging as an adult and laying more eggs before the end of the year. Otherwise there could not be multiple generations (although in some areas there is believed to be only one generation a year).