Published online by Cambridge University Press: 05 June 2009
Small galls on the leaves of Yarrow or Milfoil, Achillea Millefolium L., were first mentioned by Thomas (1873) but were investigated and described by Löw (1874) who made a new species of the causal organism under the name of Tylenchus millefolii. He dealt with the appearance, size and distribution of the galls, their presence on plants from spring to autumn and the ability of the parasite to revive from galls which had been kept dry from May to October. He described the general structure of the adult worms, gave particulars of their size and proportions, and, in addition to a sketch of a galled leaf, gave a drawing of the adult female and three views of the male tail.