ArticLteE XIV.—Forest Insects in Illinois. I. The Subfamily Och- 
thiphilinae (Diptera, Family Agromyzidae). By J. R. MAttocu. 
This paper deals with a small group of two-winged flies, or Diptera, 
belonging to the subfamily Ochthiphilinae, family Agromyzidae, and is 
intended to serve as an index both to the habits and the systematic rela- 
tions of the species. 
CHARACTERS OF SUBFAMILY 
Costa complete, extending to apex of fourth vein; fifth vein not 
flexed proximad of outer cross-vein; anal vein incomplete; both basal 
cells present, sometimes the cross-vein at base of discal cell very weak; 
vibrissae absent; postvertical bristles absent or present, when present 
convergent; tibiae without preapical bristle; interfrontal bristles ab- 
sent; orbits never with an anteriorly directed bristle; arista bare or pu- 
bescent; sternopleura with one or more bristles; propleural bristle ab- 
sent; clypeus small. 
DISTRIBUTION AND BIoLoGy oF GENERA 
This subfamily contains only seven genera. Of these, four are 
known to occur in Illinois; the other three each contain only one North 
American species and are more southern in their known distribution. 
With the exception of the genus Cryptochaetum the genera have not been 
considered as of economic importance and but little has been published 
on the biology of the other genera, this paper containing the most complete 
series of records of the larval habits extant. The predaceous habits of 
the larvae, which so far as known feed upon aphids and scale insects, 
give to the species an economic status which does not belong to any other 
subfamily in the acalyptrate Diptera, the only true aphidophagous larvae 
in the Cyclorrhapha occurring in the Syrphidae. All species of the genus 
Leucopis feed on aphids and scale insects, and it is possibly due to their 
small size that their importance as destroyers of these insects has not 
been more than casually mentioned in literature. 
I present keys to the genera of the subfamily, including the larvae 
known to me, and keys to all the North American species of the genera 
Pseudodinia and Leucopis sens. lat. 
The larvae of Leucopis are subject to attack by chalcid parasites, 
the imago of the parasite emerging through a ragged hole which it gnaws 
in the anterior portion of the dorsum of the puparium of the host. 
