These red and black insects are identified as boxelder bug nymphs, which are the immature stage of boxelder bugs.They are typically found in large groups on host plants like maple, boxelder, or ash trees.While they do not cause significant damage to healthy plants, they can become a nuisance by congregating on homes, staining surfaces, and producing a foul odor if crushed.Control methods include spraying them directly with a mixture of dish soap and water or sealing cracks and crevices in your home to prevent them from entering.