394 Annals Entomological Society of America [Vol. XI, 



which is a combination of very rapid leg movements and rapid 

 jerky bendings of the body from side to side. The body move- 

 ment is the effective factor in the locomotion. Sometimes it 

 suddenly stops in its movement and rests just beneath the 

 surface film apparently as well as beneath leaves. The locomo- 

 tion of the younger instars differs somewhat, but this is one of 

 the phases that can not be elaborated here. 



The beetle itself is never aquatic, but is commonly found on 

 grasses and other plants along shores and on the exposed por- 

 tions of aquatic vegetation, of waters suitable for the larva. 

 The imago is perfectly capable of flying, but is also a remarkably 

 powerful jumper, possessing enormously swollen hind femora. 

 Most of its motion, within its usual habitat, is by jumping. 



LIFE HISTORY. 



Egg. 



The eggs were not found in nature, but many were laid 

 under laboratory conditions by both reared and captured 

 beetles. Whether eggs are normally laid submerged could 

 unfortunately not be determined. I never saw a beetle enter 

 the water to lay eggs, nor deposit them into water, although 

 some dishes were favorably constructed for such procedure. 

 Judging from the immediate water requirements of the young 

 larva, however, it seems an entirely artificial and abnormal 

 condition that all eggs secured were laid by beetles on dry 

 objects, directly on the glass surface or on bits of leaves in small 

 vials (without water) in which many of the beetles were isolated 

 for observation. 



Eggs are laid in small, irregular masses, which are stuck to 

 the surface. Of the eggs studied, the first mass was laid during 

 the night of July 5 and hatched July 16, making an egg period 

 of 11 days. The time of oviposition of six other masses was 

 known, but in three of these all the eggs died because of mold. 

 The periods of the remaining ones were 9}/^, 103^ and 11 days. 

 The eggs of a single mass all hatch within a space of several 

 hours. The egg period is hence 93/2 to 11 days. 



Larva. 

 The only young larvae obtained were from the above men- 

 tioned egg masses in the laboratory, and were numbered in 

 groups correspondingly. Records of all of their ecdyses were 



