Collecting and mailing leaf miners
There is probably more than one generation per year, and if the leaves haven't fallen yet you could probably find the overwintering generation now (the larvae pupate and overwinter in their mines, so the collection window is longer than for leafminers that exit to pupate).
Some notes on collecting/rearing here: https://bugtracks.wordpress.com/rearing/
Basically, collect the whole mined leaves directly into an airtight container and keep it out of direct sunlight. This can be a ziplock bag if you can ensure that the larvae won't be crushed. If you want me to do the rearing, but the bag/container in a box with light packing material and send to:
Charley Eiseman
276 Old Wendell Rd
Northfield, MA 01360