28 4 ENTOMOLOGICAL NEWS. [June, '08 



under considerable pressure, so that the supply is not able to 

 float the larva, but as soon as the pressure is released and the 

 gas collects in a bubble at the tip of the tube, its buoyancy is 

 sufficient to carry the larva to the surface. This operation is 

 repeated every five minutes or so, depending upon the activity 

 of the larva. 



A test was made to determine the length of time the larva? 

 could remain submerged. For this purpose a small quantity 

 of kerosene was poured over the water in a small dish and 

 many of the larvae were found to be still active after being 

 deprived of air for a day. 



PUPA. 



The pupae are oval in shape and somewhat flattened. They 

 attain a length of 3.5 mm. and a breadth of .8 mm. The 

 thoracic breathing tubes are much shorter than in the other 

 forms, measuring about .25 mm. in length. The abdominal 

 segments are well armed with numerous short, simple and com- 

 pound spines. On the ventral surface the five segments pos- 

 terior to the tip of the wing sheaths each has two rows of these 

 spines. The first row on each segment is near its anterior 

 edge and consists of four compound spines, well separated. 

 The second row is near the posterior edge of the segment and 

 consists of from six to nine small compound spines along the 

 median line, bordered laterally by a single enlarged spine, and 

 this followed laterally by a number of smaller ones. The com- 

 pound spines consist of two or three small sharp spines borne 

 on a low circular papilla. The posterior segment bears on its 

 ventral surface a single strong compound spine, along the lat- 

 eral edge of its slightly expanded base, while the tip is ter- 

 minated by two slightly diverging strong simple spines with 

 a broad emargination between. 



The arrangement of the spines on the dorsal surface is about 

 the same as on the ventral surface. Each segment has two 

 rows, but the spines of the second row are smaller and more 

 closely set than on the ventral surface. Six of the abdominal 

 segments bear these rows of spines on their dorsal surface, 



