A fleabane flower head serves as a dining table for a Nysius seed bug in the Superstition Wilderness, Maricopa Co., Arizona, May 2009.
Lygaeidae -- Seed Bug Family
Several species of Nysius seed bugs range into the Sonoran Desert and are very catholic in their choice of seeds to feed upon. Weeds and grasses of many kinds with their often abundant seed crops can result in huge populations of these small, ca. 3mm, bugs. As bugs, they feed exclusively on liquid food through piercing-sucking mouthparts. When disturbed the bugs can release a noxious odor.
Seeds fed upon by seed bugs have reduced viability - a benefit for weed control. Once the weeds dry out, however, the bugs often move in mass in search of new food sources and may arrive at electric lights. Landing occasionally upon people they may seek moisture by inserting their proboscis into the skin - i.e. they bite and can be rather annoying! They soon move on and do not persist for blood is not their preferred meal. Vacant lots in Tucson, Phoenix, Scottsdale, Casa Grande and other desert cities can be quite weedy following wet weather which encourages these seed bugs to flourish. Keeping down weeds adjacent to dwellings and effective window screens are probably the best control strategy.
Desert Field Guide
Sonoran Desert Places
Sonoran Desert Naturalist Home Page
Michael J. Plagens, page created 08 May 2009,
updated 17 July 2021.