1923] Probable Occurence of Parthenogenesis in Ochthiphila 25 
no case have I been able to rear these larvae, nor have I been 
able to be sure that the mothers did not contain sperm — though 
it is extremely unlikely that sperm was present. This obser- 
vation makes it probable, however, that Lonchoptera reproduces 
by adult parthenogenesis, rather than by pedogenesis. 
Table III. Relative abundance of the sexes in Lonchoptera. 
State or Province 
New Hampshire 
Vermont 
Massachusetts 
New York 
New Jersey 
Ontario 
Pennsylvania 
District of Columbia 
North Carolina 
Wisconsin 
Colorado 
Santa Clara Co., California 
Monterey Co., California 
Truckee, California 
Total 
9 
1 0 
1 0 
53 0 
403 0 
53 0 
1 0 
1 0 
1 0 
2 0 
1 0 
1 0 
426 0 
23 4 
344 1 
1311 5 
Parthenogenesis has been described in the Chironomid genera 
Chironomus, Corynoneura, and Tanytarsus by Grimm (1870) 
Johannsen (1912), Goetghebuer (1913), Edwards (1919), and 
others. Eggs are produced in some cases by the larvae, in others 
by the pupae, and in still others by the imagines. In all cases in 
which imagines have been produced by parthenogenetic (in- 
cluding pedogenetic) lines, these have been females and have 
bred parthenogenetically if at all. Males are known to occur in 
these genera, and in one case even in a species that reproduces 
parthenogenetically; but in no case are males reported as arising 
from larvae known to have been produced by parthenogenesis. 
The first case of parthenogenesis recorded among the 
Diptera was that of the Cecidomyiid, Miastor, discovered by 
