Chrysanthemum gall midge

The chrysanthemum gall midge (Rhopalomyia chrysanthemi (Ahlberg)) was first noticed in 1915 in North America as a serious pest of glasshouse chrysanthemum. The first two outbreaks in England were in 1927 and 1936, and were traced to chrysanthemums imported from the United States. There have been occasional outbreaks — all under glass — since then, but the pest remains uncommon in Britain and has caused little damage since the early 1950s.