72 Forty-first Report on the State Museum. 



Noted Assemblages of Chlorops in Europe. 

 The following literature vipon the great accumulation of specimens 

 of Chlorops within buildings — a phenomenon well-known in Europe — 

 has been kindly collected, and communicated to me in letter by Baron 

 Osten Sacken — always so ready to aid in the advancement of American 

 Dij)terology: 



In September, 1831, an immense number of Chlorops gathered in a 

 room in Provost's Lodge, in Cambridge, England. An account by 

 Rev. L. Jenyns w\as published in Loudon's Magazine of Natural His- 

 tory, V, p. 302. The same phenomenon was observed in the same place 

 in September, 1870, when " there must have been millions of them." 

 It is added, however, that they occur regularly every season. (Com- 

 pare Proc. Ent. Soc. London, 1870, p. xxsiv, and 1871, p. — .) 



In 1833, the phenomenon took place in the court library in Weimar. 

 Zenker took the fly for a new species, and named it Traumatomyia 

 prodigiosa. {Frorieps Notizen, xxxv, p. 344.) 



In September, 1847, Professor Wager found millions of Chlorops in 

 the cupola of the observatory' at Warsaw, on the ceiling of a botanical 

 conservatory, and in other places. He computed that there were 

 about 17,971,200 specimens on the ceiling of the conservatory. He 

 observed these accumulations every year. All these localities are sur- 

 rounded by fields of cereals, and jorincipally wheat. Compare Bev. de 

 Zool., 1872, and Schiner's article quoted. 



Kieseuwetter, in Zittau, Saxony {Berl. Ent. Zeit., 1857, p. 172); Krauss, 

 in Stuttgart (comp. Brauer, Jahresber, 1867, p. 142); Perty, in Switz- 

 erland (ibid.) ; H. Miiller, in Lippstadt, in autumn of 1880 (comj). Katter's 

 Eidoni. Nachr., 1881, p. 17); Guerin Meneville and Laboulbene, in 

 France (Ann. Soc. Ent. Fr., 1875, p. ccvi), made similar observations. 

 Most of them took place in September. Perty saw the phenomenon 

 in March. Most of the observers notice the fancy of the flies for par- 

 ticular rooms, neglecting adjoining localities situated in aj^parently 

 similar conditions. That the object of the flies was to seek shelter 

 from cold is probable. The following observation by Aube, although 

 it does not refer to human dwellings, may be suggestive: "About the 

 end of March last, after a not very cold but a prolonged winter, I col- 

 lected thousands of Chlorops nasuta in the state of hibernation. They 

 were huddled together behind a very dense covering of ivy, on the 

 eastern wall of a building " {Ann. Soc. Ent. Fr., 1858, j). Ixxiv). 



Whether in all the above cases the same species was observed is a 

 very doubtful question. The species is called Chlorops Iceta (Wager, 

 Krauss, Laboulbene), C. nasuta (Kiesenwetter, Aube, H. Miiller), and 

 C. lineata (Perty). These identifications have no value whatever, 

 as none of them were made by competent persons, and the nomen- 

 clature, and synonymy of Chlorops is an unsolved problem even for 

 dipterologists. 



