FLIES OF THE GENUS OGCODES — SCHLINGER 243 



Predators and parasites: During the years of collecting acro- 

 cerids, I have observed several predators engaged in feeding on 

 Ogcodes adults or their eggs. Feeding on the adults were spiders of 

 the genera Dictyna, Pardosa, Tefragnatha, and Xysticus, an adult 

 nabid (probably of the si)ecles Nabis ferus), an adult reduviid, and 

 crabronids of the genus Ectemnius. Crabronids have been recorded in 

 Europe as storing their nests with adult Ogcodes, while new crabronid- 

 acrocerid associations and a summary of all available records of these 

 relationships have recently been given by Bechtel and Schlinger 

 (1957). The onl}' egg predator seen was an adult raphidid, which 

 was consuming considerable amounts of 0. adajitatus eggs that had 

 been deposited in large numbers on the dead twigs of Artemisia 

 species. 



I am not aware of any record of parasites of the late larval or pupal 

 stages of Ogcodes; however, it seems quite probable that species of 

 some hymenopterous families (such as the Pteromalidae) may be 

 found to parasitize these flies. 



Morphology 



Male genitalia: For the sake of uniformity, the terminology used 

 here follows mainly that of Sabrosky (1948). Since the genitalia of 

 all species examined offered good to excellent specific distinctions, 

 it is unfortunate that earlier and some present-day workers have 

 neglected the use of specific characters, even though Wandolleck 

 (1914) and Cole (1927) both have pointed out through illustrations 

 that distinct differences existed among the various species. Plomley 

 (1947a) described and figured the genitaha of Ogcodes jyygmaeus (as 

 0. basalis), but he did not attempt to differentiate any other species 

 by using these structures. Sabrosky (1948) was actually the first to 

 fully investigate the usefulness of male genitalia as specific characters, 

 and his work formed the basis for the present interpretations. The 

 genitalia (figured in pi. 6, fig. 31) consist of the following parts: 

 Aedeagus, claspers, 9tli tergite and cerci, 8th sternite, 8th tergite 

 (not figured), and ejaculatory apodeme. All parts of the genitalia 

 have morphological differences that distinguish the various species, 

 but those exhibiting the most significant features are the aedeagus 

 and the ejaculatory apodeme. 



The aedeagus is a long rod-shaped organ, enlarged and sheathed 

 basally. The sheath opens on the sides and becomes dorsal toward the 

 apex. The ventral side is usually notched or angled either behind 

 and/or beyond the seminal orifice (gonopore). These indentations 

 are referred to as pregonoporal and postgonoporal notches, and it is 

 this distal portion that has the definitive characteristics. 



