Lewis & Short

muscārĭus, a, um, adj. [musca], of or belonging to flies, fly- (post-Aug.).

  1. I. Adj.: aranei muscarii tela, i. e. fly-hunting, Plin. 29, 6, 38, § 131: clavus, a broad-headed nail, Vitr. 7, 3, 11.
    Hence,
  2. II. Subst.: muscā-rĭum, ii, n., a fly-flap, fly-brush, used also as a clothes-brush, made of peacocks’ tails, Mart. 14, 67 in lemm.; or hairy ox-tails, id. 14, 71 in lemm.; or horse-tails, Veg. Vet. 4, 1.
    1. B. Transf.
      1. 1. The hairy or fibrous part of plants, the umbel: semine in muscariis dependente, Plin. 12, 26, 57, § 127.
      2. 2. A closet or safe, in which writings were kept to protect them from the flies, Inscr. Rom. Viagg. a Pompeii, p. 168.