I've been experimenting this year with putting the leaves in sealed plastic bags and have been able to get some larvae to emerge from various leaf mines. Now the next step is how to keep them in an environment where they can develop.

and for leafminers that want to bury themselves to pupate, I've been transferring them to small jars of a slightly moistened sand/peat mixture. For the ones that I know need to overwinter, I've been putting the lids on the jars for the time being; for others, I leave the jar open but put it in a sealed plastic bag so I will see the adults when they emerge. With moths, since I've had too many rub off their wing scales in plastic bags, I've started putting the small jar inside another jar, with a lid screwed on and flipped upside down. Worked great for this one:

Thanks. I'll have to try some of these methods.