Mayfly (Ephemeroptera: Baetidae: possibly Callibaetis sp.) from Wisconsin. These primitive creatures are unique among insects for having a fully winged adult stage which must undergo one more molt before becoming sexually mature.
Mayfly, Ephemeroptera, from Belize. The bizarre upward-pointing eyes in males like this one are used to find females flying overhead.
Mayfly (Ephemeroptera) from Grand Teton National Park in Wyoming.