Trombidiidae, also known as red velvet mites, true velvet mites, or rain bugs, are small arachnids (eight-legged arthropods) found in plant litter and are known for their bright red color.
While adults are typically no more than 4 mm (0.16 in) in length, some species can grow larger and the largest, including the African Dinothrombium tinctorum and Indian Trombidium grandissimum, may exceed 12 mm (0.47 in). This also makes them the largest mites, if disregarding ticks engorged after feeding; unlike those, D. tinctorum and T. grandissimum are harmless to humans.