Like many plant bugs, the Red-Shouldered Bug tends to form large congregations around host plants, and even seeks winter shelters inside warm houses and buildings. Because many plants in the Soapberry family are food sources for this type of bug, it is sometimes referred to as a type of Soapberry Bug. They are fond of the sweet sap and fruit from various trees as well and have been seen feeding on figs, plums and cherry trees. Dead insects and food leftovers from humans are also welcome parts of the Red-Shouldered Bug's diet.
This species can be found on or near host plants during the spring, summer and autumn. In warmer regions, a female can produce two broods a year. They are seen almost year round in California, Florida, Texas and Mexico.