OF WASHINGTON. 263 
Dilophus, belonging to not more than two species, and all near D. sero- 
tinus, that bear labels of various dates in October, from the 8th to the 
24th, and were collected in Massachusetts and Missouri. Of these, 25 are 
99 and IT cTrp. The majority of the specimens are from Professor 
Riley's own collection, now in the National Museum. 
In regard to the length of time of transformation of these flies, so faras 
known, Meigen writes that the larvae " cast their skins at various times, 
pass the winter in the larva state, transform in the spring to pupae, 
from which in a few days the flies appear." Zetterstedt states that "the 
larvae of most of the species are said to live through the winter in dung 
and rich earth." 
It may be contended that fall appearances of these flies are due to trans- 
formations of belated individuals, but this seems hardly credible, as we 
should in that event find them as numerous through the summer as in the 
fall. The more natural inference to be drawn from these facts is that 
species which are vernal and autumnal are double-brooded, although 
these fall appearances may be due to accelerated development. Of these 
species occurring both in the spring and fall, we have in America Bibio 
albipennis, Dilophus serotinus, and an undetermined species of Dilophtts. 
DECEMBER 5, i 
Eleven persons present. President Schwarz in the chair. 
Prof. Riley presented a communication on the oviposition of 
Diptera in which he reviewed the subject of piercing ovipositors 
in different orders of insects. He stated that in the order Diptera 
they are very rare, and that it is a broad rule with but few ex- 
ceptions, that when the Diptera in any way pierce or sting it is 
through modifications of the mouth-parts. In the Trypetidce^ 
however, as also in some of the allied families of Ortalidcz and 
Lonchceidcz, the ovipositor is modified and fitted for puncturing, 
and he instanced cases like Trypeta pomonella and T. lugens in 
which the ovipositors were well adapted to piercing in the one 
case the apple, and the other case the orange, and placing their 
eggs in the fruit on the pulp of which the larvae live. 
Prof. Riley also presented a note on the genus Lestophonus, 
stating that upon receipt of fresh material from Mr. Frazer S. 
Crawford and some further notes from him, he had carefully gone 
over again the material in the National Museum collection and 
had concluded that Dr. Williston was wrong, and Mr. Skuse, 
