Which insect is characterized by red and black coloration, particularly in its nymph stage?

The Boxelder Bug is characterized by its distinctive red and black coloration, especially prominent in its nymph stage. These nymphs exhibit a bright red hue with black markings, making them easily identifiable. The coloration serves as a form of aposematism, warning potential predators of their unpalatable nature.

In contrast, ants generally do not display such bold colors and have a more uniform coloration. Ladybugs, while they can be red and black, are better known for their adult forms and have a different life cycle appearance than the specific coloration of Boxelder Bug nymphs. Stink bugs, on the other hand, often exhibit green or brown shades in their adult forms and do not share the same striking coloration pattern as the Boxelder Bug. Therefore, the unique characteristics of the Boxelder Bug's nymph stage make it the correct answer for this question.