320 THE BLOWFLIES oF NortTH AMERICA 
The generic name Onesia has been retained for two species of 
North American ealliphorine flies because the present generic 
treatments of the group are not satisfactory. Sufficiently long 
series of such flies from which to evaluate the numerous charac- 
ters have not been available. It is impossible for me to know 
which of the characters are of generic importance and which 
are of but specific value. It appears that this group of flies may 
have been too finely divided. Onesia in the broad sense includes 
about fifteen species, all of which are very similar. Most of 
them are Palearctic. The species assigned by Robineau-Desvoidy 
to his genus Melinda may be easily separated from the rest of 
Onesia by the lack of pile on the dise of the lower squamal lobe. 
But all of the remaining species are so similar in most respects 
that to divide them would conceal their unmistakable relation- 
ship to each other, although it is fully realized that there are 
a number of characters in the chaetotaxy of the species that 
might be considered of generic value. Subgeneric names for 
the species groups might be useful. If the characters now used 
for the separation of these genera in the Palearctic region are 
found to be constant, and of generic value, then the two North 
American species referred to Onesia below must be placed in 
two different new genera. These possibly distinct genera may 
be separated by the following key. 
1. Lower squamal lobe setose on dise above............... 2 
Lower squamal lobe bare above. . Melinda Robineau-Desvoidy 
2. Lower squamal lobe with black hair above............ whe 
Lower squamal lobe with white hair above............... 
Rar Eee TS an Me eC RAE us8g 0 Abonesia Villeneuve. 
3. Preacrostichal bristles present. .2......%..... 0 eee 4 
Preacrostichal bristles absent....... Macronesia Villeneuve. — 
4. Two or more postacrostichal bristles................... 5 
One postacrostichal bristle......... Pseudonesia Villeneuve. 
5. Hindmost preintraalar bristle absent...... 22. 7. eee 
Ptiuities AASaM, Sewer Ok. neers Onesia Robineau-Desvoidy. 
Hindmost preintraalar bristle present..............0saeeee 
- The genus Onesia appears to be a homogeneous group, and 
Keilin (1915) in Europe and Fuller (1933) in Australia show 
that the biologies are similar. The latter author has reported 
upon the biology, habits, and immature stages of Onesia accepta 
Malloch, which is parasitic upon Microscolex and other earth- 
