Stelis

Stelis are small to medium-sized parasitic megachilids. Males and females have a similar appearance, with a robust build and almost no body hair. They are mainly black, but some species have yellow or cream-colored markings, especially in the abdomen. The hosts of Stelis are other megachilids, such as Heriades, Chelostoma, Osmia or Anthidium. Females have been observed returning several times to the same host nest, attempting to lay an egg in each brood cell before the burrow is closed. They may be difficult to spot in the field, but they can occasionally be found in insect hotel inhabited by their targets.