PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 637 



it thou seems almost deprived of motiou." He acliiiowledges tliat liis 

 P. autnmnalis is also a synonym of rndis. 



It will be seen from these facts that the species is not easily identified. 

 This is accounted for on several grounds : 1st, the flies when they have 

 frequented pollen-bearing flowers present a much brighter, yellowish 

 appearance; 2d, the tufts of hairs which characterize it are very easily 

 rubbed off; 3d, most of the insects of the family, as well as other Dip- 

 tera of allied families, have a great tendency to grease, i. e., they soon 

 acquire in the cabinet a greasy, dark-colored aspect in which the char- 

 acteristic markings are obliterated. 



The genus, w^hich is numerous in species and individuals, is chiefly 

 distinguished by the bulging middle face ; by the base of the antennae 

 being generally fulvous in color, and by the tufts of hairs at the sides 

 of the thorax, to which last character the generic name alludes. The 

 old genus Musca has been subdivided into numerous genera founded, 

 as in this instance, on rather trifling characters, so that it becomes very 

 difficult to separate some of them or to properly refer the species to 

 them. 



There are two authentic specimens of Follenia rudis, determined by 

 Baron Osten Sacken in my cabinet now in the National Museum, so that 

 there can be no question as to the species. 



In reference to the habits of the species it will be seen that v.^hat I 

 liave quoted from other authors corresponds very well with the facts 

 as communicated by Mr. Dall, though I find no mention of any such 

 unusual swarming in houses and working under bed clothing as com- 

 municated by his correspondent. The species is not infrequent in the 

 fall of the year in houses in Washington and is readily distinguished 

 from the common house-fly, even by an ordinary observer, by its larger 

 size and more sluggish movements. The specimens submitted by Dr. 

 Baker and received from Maine are specifically identical. Dr. S. W. 

 Wilhston, of New Haven, Conn., writes me that he thinks he observed 

 it in numbers clumsily crawling on the snow during mild weather in 

 February and March. 



Nothing definite is recorded of the larval habits and development of 

 the species, though, speaking of the genus, Eobineau-Desvoidy remarks 

 that the eggs are laid in manure and in decomposing animal and veg- 

 etable matter. The larva doubtless lives in such decomposing sub- 

 stances. 



It is not improbable that in parts of New York the species may have 

 acquired more troublesome habits than it has elsewhere, for among the 

 Diptera we have such instances of peculiar and injurious habits being 

 locally developed, as in Trypeta pomoneUa Walsh, which in the West 

 confines its work to the wild crabs and haws, while in the Eastern States 

 it proves injurious to cultivated apples. LiiclUa macellariais a grievous 

 pest in the Southwest, producing the well-known screw-worm so inju- 

 rious to stock, whereas in the more northern States we never hear of 

 such injury. 



