Burrowing bug pigmentation.

Cydnidae bug (also termed the burrowing bug) are arthropods of the order Hemiptera, that are recognized by their morphological adaptations for digging. They release an odorous substance from special glands that serve as self-defense, causing pigmented macules when in contact with human skin, especially during the rainy season. Knowledge of this rarely described condition can help avoid unnecessary investigation(s).