90 MR. F. BALFOUR-BROVVNE ON THE LIFE-HISTORY 



Agrionid dragonfly, Hydrohius fuscipes and Dytiscus, keeping 

 records of individuals, each in a separate tumbler, but I could 

 find no food which they would eat. The newly- hatched Pelohius 

 larva is only about 2 liim. long in body-length, so that minute 

 food was obviously necessary, but Paramcecium, upon which I 

 fed the newly-hatched dragonfly nymphs, had no attraction for 

 them, and minute alga3, Cladocera, and Oopepoda were equally 

 useless. I noticed, when I placed a larva in a tumbler with a 

 layer of mud at the bottom, that this mud was continually 

 examined and even burrowed into, which suggested that the 

 necessary food wns some mud-inhabiting species. As, however, 

 these larvae also died, I made a journey to one of the ponds where 

 the beetle occurred and brought home a supply of mud from 

 there, and, on using this in the tumblers, it was at once obvious 

 that the food-problem was solved. This mud was swarming with 

 T'ubifex, and it was most interesting to watch the larva hunting 

 for and capturing its prey. It would move slowly over the 

 surface, touching it with its antennae and palpi, and, on dis- 

 covering a Tubifex burrow, the larva would either at once leap 

 into it, sometimes disappearing except for the apices of its 

 " tails," or it would sit and watch, like a cat at a mouse-hole, its 

 action presumably depending vipon the position of the worm in 

 the burrow. Sometimes the snatch at the prey would fail and 

 the larva would move elsewhere, but with these first-stage larvte 

 it was difficult to decide whether the pounce had been successful, 

 as it was rare for, the larva to appear from the burrow with the 

 worm in its mouth. With the larger larvas one could see the 

 struggle, the worm tidying to withdraw to the bottom of the burrow, 

 and the larva, as it were, sitting back upon its haunches and 

 pulling with all its might to get the worm out. In the case of 

 these lai-ger larva?, however, the feeding was sometimes done in 

 the burrow. 



The feeding process is rather peculiar ; the larva sits motionless 

 with most of the worm projecting from its mouth and wriggling 

 furiously, the larva to all appearance doing nothing ; suddenly, 

 however, the latter makes a gulp, and a little of the projecting 

 part of the worm disappears into the mouth. After a short 

 interval another gulp takes place, and thus by a series of gulps 

 the worm disappears down the " throat." The larva apparently 

 always seizes the worm by the end, never by the middle. 



So far as I could find, Tubifex is the only food of the larval 

 Pelohius, as, although I tried various other materials and could 

 get the larva? to eat Chironomus larvae, I never succeeded in 

 rearing one on any diet other than the little red worm. 



4 (f ) The Stomodceum of the Larva. 



The gulping down of the Avorm struck me as rather extra- 

 ordinar3\ There was no chewing or biting, and yet an examination 

 of the contents of the alimentary canal always showed chewed-up 



