Panonychus ulmi, the European red mite, is a species of mite which is a major agricultural pest of fruit trees. It has a high reproductive rate, a short generation time (21 days at 20 °C or 68 °F) and produces many broods in a year, all of which contribute to its pest status. It has a cosmopolitan distribution, and a very wide host range, having been found on the following plants: P. ulmi was first described by Carl Ludwig Koch in 1836, under the name Tetranychus ulmi. It has also been known under a number of synonyms: