Family Gomphidae. These are often called clubtails. the name refers to the club like widening near the end of the abdomen.

Gomphurus externus (dorsal view of adult)

Gomphurus externus (Hagen in Selys, 1858) [Plains clubtail] (Peoria Co.)

Phanogomphus exilis (dorsal view of adult)

Phanogomphus exilis (Selys, 1854) [Lancet clubtail] (Fulton Co.)

Phanogomphus grasslinellus (dorsal view of adult)

Phanogomphus graslinellus (Walsh, 1862) [Pronghorn clubtail] (Peoria Co.)