As far as lepidoptera, you may be referring to the Karner Blue butterfly, whose habitat has virtually been lost due to logging and destruction of habitat. It's host plant is lupine perennis.

Is there a native plant or insect group, or you could also check with the Universities there. Someone is usually an expert in entymology and can help you out with host plants. Also google "Michigan Dragonflies". You may find the endangered species on a list somewhere, with a list of host plants. I don't know if dragonflies have host plants or not since that's not my area of expertise.

Good luck! The Karner Blue surely needs your help.

Susan