In the "fly fishers guide to Pennsylvania" midges are listed in the hatch chart often. Would he be referring to using nymphs or dry flies? It doesn't specify.
Both really...midges "hatch" all year round. Have larvae, pupa and adult/dries in brown, black, cream, olive..experimental colors as well...from 18 to 99..ha ha
Taken, there is a lot of info online regarding midge fishing. But a great book to get ahold of is Midge Magic by Don Holbrook. Also, don't be afraid of fishing something so small. Trout eat a lot of midges.