An account is provided of the discovery of Simacauda dicommatias (Meyrick, 1931) (Incurvariidae) at 26 sites in Cornwall, England, all in the larval stage, being initially leafminers then case-bearers on South American members of the Myrtaceae, mainly Luma apiculata (DC.) Burret, with moths being reared, and species identification confirmed by genitalic examination. This is the first time that the species has been found in the British Isles and it is unknown in mainland Europe. S. dicommatias is native to Argentina and Chile where it occurs in Andean (Valdivian) temperate rainforests. The biology appears to be unknown there, although adults have been collected around stands of L. apiculata. The generic identity is additionally confirmed by a DNA barcode (658 base pairs) obtained from the abdomen of one specimen from Cornwall. This matches (within 1.69% divergence for 296 comparable nucleotides) a COI fragment on BOLD from a specimen collected in Parque Nacional Puyehue, Chile, which is there misidentified as Simacauda virescens Nielsen & Davis, 1981, but is 8.75% divergent from another two short sequences (correctly) so identified. It is known that William Lobb, whilst employed by James Veitch & Son, imported L. apiculata (now an invasive species in the British Isles), with one or more other Chilean Myrtaceae in the mid-1840s. It remains to be tested if S. dicommatias may prove to be the earliest known example of an established adventive insect accidentally introduced from South America to the British Isles.

Two new European species of Microgaster are described from reared material. Microgaster nervosae sp. nov. parasitizes Agonopterix species (Depressariidae) on Ulex and Genista in Britain, and a key is provided to separate it from two other British Microgaster species that parasitize other Agonopterix, with host information. Microgaster monetae sp. nov., a parasitoid of Polychrysia monetae (Noctuidae), is described from Austrian specimens. The host repertoires of Microgaster nobilis and M. australis, two European species that are regular parasitoids of Hesperiidae: Pyrginae in the Mediterranean region, are discussed on the basis of reared material in NMS. Some new country records (France, Israel, Portugal, Spain) of already established Microgaster species are given.

An illustrated account is given of the larval feeding, larva and pupa of Stenolechia gemmella (Linnaeus, 1758), whose larva is an internal feeder in the green stems of deciduous Quercus spp. Accounts published in the British and European literature are considered.

Cotesia balearica Shaw & Colom sp. nov. is described as a solitary endemic parasitoid of Gonepteryx cleopatra in the Balearic Islands. A key is given to the three known Cotesia parasitoids of Gonepteryx in Europe, and biological notes are given for each species. Some new country records are given.