242 



HABITS OF LARVAE 



The larvae of Rhyphus are found in manure, decaying vegetation, 

 and occasionally in cesspools or bodies of stagnant or impure water; 

 those of Mycetobia are found in wounds on trees, feeding upon the 

 exuding sap and its attendant fungus. Rarely both genera are found 

 together. 



I have found nematode parasites in the larvae of Mycetobia at 

 Urbana, 111. 



HABITS OF IMAGINES 



Both Rhyphus and Mycetobia are found commonly on tree- 

 trunks and on windows in houses. They feed upon nectar and liquid 

 matter. 



Keys to Genera 



larvae 



1. All segments conspicuously marked with dark brown; head but lit- 

 tle shorter than prothorax; apical segment with 5 short but dis- 

 tinct processes round the spiracular disc Rhyphus. 



— Only the thoracic segments conspicuously marked, the markings yel- 



lowish or very pale brown ; head conspicuously shorter than pro- 

 thorax ; apical segment with microscopic processes round the spi- 

 racular disc which are invisible except under a very high-power 

 lens Mycetobia. 



PUPAE 



1. Spiracular opening of the prothorax rather large, circular, distinct- 

 ly but not greatly elevated ; thorns in transverse series near pos- 

 terior margin of each abdominal segment rather widely separated 

 Rhyphus. 



— Spiracular opening of moderate size, situated upon a conspicuous 



tubercle, with a ridge-like elevation extending eaudad of it ; thorns 

 in transverse series near posterior margin of each abdominal seg- 

 ment close together, generally contiguous Mycetobia. 



IMAGINES 



1. Discal cell of wing absent Mycetobia. 



— Discal cell of wing present 2 



2. All branches of radius ending in margin of wing Rhyphus. 



— Second branch of radius ending in first Olbiogaster. 



Rhyphus Latreille 



I have but one species of this genus represented by all three stages, 

 consequently it is unnecessary to summarize the generic characters. 



