HABITS OF THE LARVA OF BELLURA MELANOPYGA. 



In this connection another set of experiments was carried on 

 in which the infested lily leaves were staked down under water to a 

 depth of six or seven inches and the behavior of the larva? under 

 these new conditions noted. Each larva came to the top of the 

 burrow and gradually pushed the posterior end out through the 

 entrance, continually searching in a random fashion for the sur- 

 face film. Ultimately it loosened its hold, came to the surface, 

 and swam about until it came to another lily leaf. In some cases 

 larvae lived for 45 minutes under water before they would release 

 the hold and come to the top. 



Expired Air. After a larva has been at the bottom of a burrow 

 for a brief interval one or two bubbles usually rise to the top. 

 This happens commonly at the end of the period below r and just 

 before the beginning of the trip to the top. These bubbles 

 probably represent, in part at least, expired air w T hich is expelled 

 from the trachea?. 



The Breathing Position. Except when the larva voluntarily 

 leaves the burrow, it only tips the surface with the posterior end 

 when taking air. Normally only the dorsal surface of XII 

 and XIII and just enough of the posterior margin of XI to include 

 the large dorsal spiracles is above the surface film, the other 

 portions of the body remaining under water. \Yhen the larva 

 comes to rest at the breathing position the terminal spiracles pull 

 down the surface film, forming a small conical depression. When 

 in this position the larva is very sensitive to surface disturbances 

 and responds quickly to them by retreating into the burrow. 

 Thus in making observations on the breathing activities it was 

 very necessary to avoid making even the smallest ripples or 

 swells. Very tiny jars on the leaf produced the same response. 

 The alighting of a small insect on the same lily leaf was sufficient 

 to cause the larva to dodge below. It is very probable that this 

 response is responsible for the avoidance of man)- attacks by 

 predaceous enemies. 



Breathing Movements. If a larva in the breathing position be 

 watched carefully it will be noted that certain rhythmic move- 

 ments are performed. These movements occur at intervals of 

 from two to three seconds and appear to consist of an alternate 

 contraction and expansion of the exposed region. 



