l6o S. J. HOLMES. 



las are seized and sucked out without much difficulty. While 

 mature Ranatras will live together peaceably for a long time the 

 young readily attack and devour one another. If several young 

 are kept in the same dish it will be found that, in the course of 

 a few days, a majority of them will have fallen victims to a few 

 successful combatants. If a young Ranatra seizes another near 

 the middle of the body it is usually able to bring its victim up to 

 its proboscis, the tip of which is moved about in search of a soft 

 spot in the armor of the unfortunate individual, whose blood is 

 then deliberately sucked out notwithstanding the creature's 

 struggles. Often a Ranatra is seized by one of its legs. This 

 is usually not resented until its captor, after pushing the tip of 

 its proboscis along the leg until it finds one of the joints, begins 

 to insert its piercing stylets through the soft integument, when a 

 vigorous struggle ensues. 



Young Ranatras are exceedingly voracious creatures, as they 

 will kill and suck out several insects as large as themselves in 

 the course of a day. Their food consists mainly of small swim- 

 ming forms, chiefly small crustaceans and insects, which come 

 near the surface of the water. Like the adults, they are very 

 efficient enemies of the larvae of mosquitoes. They do not pur- 

 sue their prey, and they seldom catch forms that keep in close 

 contact with solid objects. They are like so many traps set 

 ready to seize anything that comes in contact with them. Often, 

 however, an object is grabbed at if it passes near a Ranatra with- 

 out coming into actual contact with it. This action is probably 

 a response to the impact of the water. If a Ranatra is hungry, 

 touching the surface film with a needle near the insect will often 

 cause it to grab about wildly in the effort to seize whatever may 

 have caused the disturbance. An object of too large or threat- 

 ening appearance causes the young Ranatra to jerk back its first 

 pair of legs, but there are no efforts to swim away from danger. 

 When this reaction occurs the insect cannot be induced to take 

 food for some time. 



The reactions of young Ranatras to light are not nearly so 

 vigorous and decided as those of the adult. A feeble positive 

 phototaxis is manifested the first day after hatching and increases 

 gradually as the insect grows older. Individuals a v/eek old are 



