Macara alydda is a moth of the family Megalopygidae. It was described by Herbert Druce in 1887. It is found in Costa Rica and Napo Province, Ecuador. The habitat consists of montane cloud forests. The forewings are dark silky brown, with the outer margin, from the apex to the anal angle, broadly banded with pale fawn. There is a series of silvery white spots (which have black dots on the side nearest the base) on the inner side of the pale colour. There are two black spots close to the apex and a pale-fawn mark at the end of the cell. The hindwings are uniform pale silky grey.