Giant-insect
Guides
Microstylum morosum
Giant Prairie Robber Fly
Microstylum morosum is the largest robber fly in North America, with body lengths reaching 35–50 mm. The species was long considered endemic to Texas until range extensions were documented into Oklahoma, Kansas, Arkansas, Missouri, and southwestern states. It inhabits prairie and grassland ecosystems, where adults are active predators. The species exhibits distinctive emerald-green eyes and a relatively hairless, streamlined body compared to other large asilids.