|Ecological notes on male Mydas xanthopterus (Loew) (Diptera: Mydidae) and their interactions with Hemipepsis ustulata Dahlbohm (Hymenoptera: Pompilidae)|
|biology, Mydas, Mydidae, Mydinae, Nearctic|
Observations of the hilltopping male of Mydas xanthopterus (Loew) were made on a ridge near Portal, Arizona during June-August 1978. Male flies were active from sunrise until late morning, defending portions of hilltop bushes and small trees. Territories were defended prior to study initiation in late June until about 18 July after which only scattered individuals remained on the hilltop. Territorial aggressiveness was directed toward all nearby flying objects. The co-occurring wasps Hemipepsis ustulata Dahlbohm and Polistes canadensis (Cresson) also defended sites on the hilltop. H. ustulata males more aggressively defended their territories against Mydas males than against Polistes males, possibly due to mimetic similarity of Mydas and Hemipepsis.