As the common name implies, it is a large bug that feeds on mesquite trees of the American Southwest and Northwestern Mexico.

[2] Thasus neocalifornicus inhabits the Sonoran Desert from southwestern Arizona to the Mexican state of Baja California Sur and can be plentiful depending on the season.

Most populations in the United States occur in the Tucson area, and around the southern tip of Baja California Sur in Mexico.

They have an aposematic white and red coloration, while adults are dark brown with crimson and black striped legs and antennae.

[1] Adults rely on muted coloration and heavier armor for defense, while nymphs employ noxious chemicals.

[7] A study by Becerra et al. found that individuals without the symbiotic bacteria Wolbachia were unable to produce alarm pheromones or defensive chemicals.

The study found that Burkholderia was present in neither the eggs nor all young nymphs, meaning the symbiont is acquired post-hatching.

A study by Czaplewski et al. conducted near Tucson found that when nighttime temperatures dropped in late summer, the adult bugs became sluggish on the edges of trees.