Identification of larval instars of the Phthirapteran Ectoparasite Campanulotes bidentatus compar (Burmeister, 1838) by the setal patterns Silke Kayß * ,1 , Michael Ohl 1 , and Ragnar Kinzelbach ** ,2 1 Museum fu ¨ r Naturkunde der Humboldt-Universita ¨ t zu Berlin, Invalidenstraße 43, D-10115 Berlin, Germany 2 Universita ¨t Rostock, Allgemeine & Spezielle Zoologie, Universita ¨ tsplatz 2, D-18055 Rostock, Germany Received December 2004, accepted June 2005 Published online 20 April 2006 With 11 figures and 1 table Key words: Phthiraptera, Campanulotes , ectoparasites, chewing lice, larval instars, larval morphology, chaetotaxy, scanning electron microscopy. Abstract Morphological differences between larval instars of the chewing lice Campanulotes bidentatus compar (Burmeister, 1838) based on the setal pattern of the tempora and the mesometathorax are evaluated for the reliable identification. This character complex has not been described previously for this species. Specimens of lice have been collected from the plumage of feral pigeons (Columba livia forma domestica) from the city of Rostock (Germany). In order to determine species, sex and larval stages lice have been examined by light and by scanning electron microscopy. Additional linear measurements have been taken for the various stages. # 2006 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim Introduction A wealth of literature on the life history and the morphology of avian lice (“Ischnocera”), particularly on the discrimination of larval instars, has been published (Eichler 1936; Wilson 1939; Emerson 1961; Złotorzycka & Lucinska 1967; von Ke ´ ler 1969; Złotorzycka et al. 1974; Mey 1997; Mey et al. 2002). Larval stages of chewing lice are usually identified by size, the degree of sclerotisation or the chaetotaxy of certain parts of the body. Martin (1934) gave a detailed discussion of the life history of the pigeon louse Columbicola c. columbae (Linnaeus) and described the differences between all larval instars. Wilson (1939) discussed morphological characters of larval instars of Lipeurus caponis (Linnaeus, 1758). Nelson & Murray (1971) made attempts to establish laboratory colonies of C. bidentatus compar on artificial conditions. Mey (1994) gave an annotated list of publica- tions on the larval morphology of Ischnoceran bird biting lice. However, the time-consuming discrimination of larval instars by size measure- ments is still necessary for any kind of study in phthirapteran biology. In the recent study mor- phological differences have been employed in order to identify larval instars of C. bidentatus compar based on the setal pattern of the tem- pora and mesometathorax that have not been described previously. Material and methods A large number of specimens of C. bidentatus compar (n ¼ 6971) were collected by visual examination of the plum- age of feral street pigeons (C. livia domestica). The birds have been captured in the city of Rostock (54  06 0 N, 12  08 0 E) Mitt. Mus. Nat.kd. Berl., Dtsch. entomol. Z. 53 (2006) 1, 86–90 / DOI 10.1002/mmnd.200600008 # 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim * Corresponding author: e-mail: silke.kayss@museum.hu-berlin.de ** e-mail: ragnar.kinzelbach@biologie.uni-rostock.de