266 ENTOMOLOGICAL NEWS. (July, 'iN 



bottom under water for extended periods. They seem to have 

 an aversion for sunlight and will descend and bury them- 

 selves in the debris at the bottom of the container as soon as 

 it is placed where the sun can shine on it. Usually when pro- 

 gressing through the water they move backwards with a quick, 

 jerking, sideways movement of the abdominal segments. They 

 are rapid in movement and when at the bottom of a dish are 

 difficult to take up in a pipette on account of being able to 

 propel themselves through the debris so rapidly. They sel- 

 dom live longer than five or six days in a jar which does not 

 contain Pistia plants. 



That the pupa forms and makes it escape from the larval 

 skin without causing the latter to become detached from the 

 air-supplying rootlet is quite evident as the empty larval skins 

 are frequently found still attached. 



Like the larvae, the pupae also attach themselves to the 

 Pistia and secure their air supply from the porous rootlets. 

 The respiratory tubes of a pupa are long and slender and 

 curve backward, downward and slightly outward. When at- 

 tached to a plant the tips of these tubes are sometimes direct- 

 ed inward and inserted in the root so closely together that they 

 nearly join in the plant tissue. At other times they are in- 

 serted with nearly the width of the pupa between the two 

 tips. We have never observed these tubes inserted widely 

 apart as the outward curve of the tips would lead one to sus- 

 pect would be the procedure. The pupae often hang sus- 

 pended by the air-siphons with the head and dorsal surface 

 proximate to the rootlet. 



When placed in breeding jars the pupae survive and seem 

 to change to imagines as readily as under natural conditions, 

 whether the plants are present or not. If plants are present 

 the pupae soon affix themselves to the rootlets and remain 

 attached during the pupal period. If no plants are present 

 they obtain their air-supply at the surface of the water like 

 other pupae, and are able to move about at either the surface 

 or the bottom with apparently equal facility. The pupal period 

 ranges from two to five days. A three-day period seems to 

 be the average. 



