Abstract
Taxonomic notes and a key are provided for the eleven species ofAchrysocharoidesfound in Britain includingA.carpinisp.n. Several forms of undetermined specific status are also described. Two species‐groups are erected: thelatreilliigroup and theaty sgroup. All British species have been reared as parasites only of leaf‐mining larval Gracillariidae (Lepidoptera); one brood is here recorded fromCaloptiliaonQuercus;all other rearings are fromPhyllono‐rycterspecies. Parasite—host associations and speciation within the genus are discussed.