For a systematic memoir refer to Mayr, Verh. zool.-bot. Ges. Wien, xxxv. 1885, p. 147, etc.
Insect Life, iv. 1891, p. 193.
Tosquinet, Ann. Soc. ent. Belgique, xxxviii. 1894, p. 694.
Ichneum. Forst. Ins. 1844, p. 81.
Mitt. schweizer. ent. Ges. iv. 1876, p. 518.