-3- 



genera, two of which also occur in the U.S.A., namely Leucotrichia 

 and Zumatrichia . Wiggins (1977) , considers the genera Neotrichia 

 and Mayatrichia to be a subfamily unit after studying the larvae 

 but did not create a subfamily to contain them. 



Table for determination of Hydrotilidae genera 



1. Foretibia without apical spur. 

 Foretibia with apical spur. 



2. Spur formula: 0-2-3; ocelli present. 



Spur formula: 0-2-4 or 0-3-4; ocelli pre- 

 sent or absent. 



3. Spur formula: 0-2-4. 

 Spur formula: 0-3-4. 



4. Ocelli present. 

 Ocelli absent. 



5. Metascutellum pentangular. 

 Metascutellum triangular. 



8. 



-2 

 -10 



Neotrichia 



-3 



-4 

 -6 



-5 

 -Hydroptilia 



-Rioptila 

 -Mayatrichia 



6. Ocelli absent; metascutellum rectangular. -Orthotrichia 



Ocelli present; metascutellum not rec- 

 tangular . 



-7 



Mesoscutellum with fracture line from lateral 



angle to lateral angle. Ochrotrichia 



No fracture line across mesoscutellum. 



Mesoscutellum diamond shape; wide area pos- 

 terior to postero-dorsal edge. 



Mesoscutellum with anterior edge evenly 

 curved; postero-dorsal edge close to or 

 touching posterior margin on meson. 



Postero-dorsal edge of mesoscutellum 



touching posterior edge on meson; metascu- 

 tellum extends to lateral margin of seg- 

 ment. 



Postero-dorsal edge of mesoscutellum sepa- 

 rated from posterior edge; metascutellum 

 connected to lateral margin by straplike 

 piece. 



-8 



-Agraylea 



-9 



-Oxyethira 



-Ithytrichia 



