Observations on Hymenopterous parasites of frit fly Oscinella frit L. on oats.
The following is virtually the author's summary. Observations in southern England in 1964-67 showed that the period when most of the Hymenopterous parasites emerged from the tiller generation of Oscinella frit L. on oats coincided with the flight of the adult flies from the panicles and was too late for them to attack the immature stages. Halticoptera fuscicornis (Wlk.), Callitula bicolor Spin, and Cyrtogaster vulgaris Wlk., which emerged during July, were the only ones able to parasitize the immature stages of O. frit in the grains. Very few immature individuals of the panicle generation were parasitized, and it is concluded that O. frit in Britain has a generation out of phase with the life-history of its parasites.