32 S. J. HOLMES 



They sometimes fly to lights at night, but some species manifest 

 little tendency to go towards the light under any conditions. 

 CuUseta inornaius, Aedes fuscus and two species of Culex, C. 

 pipiens and C. territans, with which I have experimented, show 

 a marked positive photo taxis. They keep on the sides of their 

 cages nearest the window and in the dark room they follow the 

 light in any direction. When collecting them in vials it is only 

 necessary to hold the closed end towards the sun to be able to 

 put in the cork without the insects escaping. This positive 

 phototaxis is shown as strongly the first day after emergence as 

 after specimens have been kept some weeks in confinement. 

 After a full meal, although more sluggish, they are still positive. 

 The males show the same positive reactions as the females. 



