1833.] Entomology. 83 
and work into woolen stuff and yarn, apparently trying to suck up 
and extract the oily or fatty matter contained therein. 
The flies received by these gentlemen were referred to us for 
determination. They proved to be the Musca rudis Fabricius, a 
species common to Europe and America, and redescribed by Har- 
ris (Entom. Corresp. of T. W. Harris, p. 336) as Musca familiaris. 
Musca obscura Fabr., and Pollenia autumnalis R-D., are also syno- 
nyms. Robineau Desvoidy, in dividing up the old genus Musca 
made rudis the type of his genus Pollenia, and enumerated about 
forty species. Although most of these species are very numerous 
in individuals, nothing definite is known in regard to their larval 
habits and development, though the last named author remarks 
that the eggs are laid in decomposing animal and vegetable 
matter. 
The general habit of the species of entering dwelling houses in 
the fall.of the year has been noted by both Harris and Robineau- 
Desvoidy, but we recall nothing in print that records their being 
such a nuisance to housekeepers. Enormous swarms of certain Dip- 
tera have occasionally been observed,! but no satisfactory explan- 
ation has so far been given for their formation. In the case of our 
Pollenia it seems to seek shelter in houses against the cold of 
winter; but the flies do not enter the houses in a single swarm as 
certain species of Chlorops have been observed to do; they grad- 
ually accumulate. The reasons why certain houses prove so 
attractive to the flies year after year, are difficult to explain. Wy- 
enbergh (l. c.) records the swarming of Pollenia atramentaria and 
P. vespillo in the same building for seven successive . His 
explanation that in this instance certain conditions facilitated the 
entrance of the flies but rendered their exit difficult, appears quite 
plausible.— C. V. Riley. i 
NAPHTHALINE Coxes.—Mr. C. Blake, of Philadelphia, has writ- 
repellants will deter no one from giving the cones a trial. We 
would add that we have never attributed to the cones the power 
of causing the greasing of cabinet specimens, but simply of en- 
couraging, in a similar way as does camphor, the tendency already 
existing. We have found that the glazed and relaxed appearance 
of our Lepidoptera which followed their use, was but transient, 
and due, doubtless, to the first rapid evaporation of the material 
which is often deposited on the insects in minute crystals. Mr. 
Blake claims further that the cones do not stain. Our experiences 
1 Vide H. Weyenbergh’s Dipterous swarms in Verh. Zool.-bot, Ver., 
Wien, 1871, Vor, ven n et a: A - 
