Thank you for contacting Iowa State University Department of Entomology. We appreciate your interest in insects and are glad to answer your questions

The insects are called soldier beetles. Sometimes they are called leatherwing beetles in reference to the leathery (rather than crunchy) texture of the wing covers.

The specific species found on flowers in the fall of the year in Iowa is usually the goldenrod soldier beetle, also called the Pennsylvania soldier beetle, Chauliognathus pensylvanicus.

Soldier beetles are beneficial because the larvae feed on other insects. My experience is that the larvae are under mulch and plant debris. I don't think they are a predator on monarch butterfly eggs on milkweed leaves. Soldier beetle adults primarily feed on nectar and pollen and would not interfere with monarch caterpillars or butterflies.

Soldier beetles are most closely related to lightningbugs which have a similar size and shape but also have the light-producing organ on the underside of the abdomen. Soldier beetles do not have a light-producing organ.