160 THE UNIVERSITY SCIENCE BULLETIN. 



Oviposition. Wessenberg-Lund says that with Ranatras the eggs are 

 laid in early morning. Fred Enoch, 1909, gives the most complete ac- 

 count we have. His observations were upon R. liniaris : 



"Last week I had the pleasure of observing the female engaged in ovi- 

 positing on a floating leaf of Alisma, the edges of which were tightly 

 grasped by the second and third legs, while the first were held close to- 

 gether, high up on a line with the body, which slanted down from the 

 head at about an angle of 30 degrees, the head being an inch above the 

 leaf. The ovipositor was extruded, and the tip pressed by a downward 

 and forward movement into the leaf, until forced through, when it was 

 partially withdrawn, opened, and an egg placed in the hole. The long 

 lateral filaments sprung open as the ovipositor was withdrawn. She 

 moved along a quarter of an inch, and the process of boring the hole 

 repeated, the long respiratory tubes resting on the fork of the last laid, 

 which was pressed home until the tip of the egg was just level with the 

 surface of the leaf. The eggs are also laid in half decayed stems of 

 Alisma, and sometimes, though not so frequently, in healthy green stems. 

 I have several times bred PresUvichia aquatica Lubbock from eggs of 

 Ranatra." 



The writer has not seen the process, though he has watched for it a 

 number of times. He disturbed one in the act at Beebe Lake, July 11. 

 Eggs were laid in large numbers in a pool on Six Mile Creek, near 

 Ithaca, N. Y., during June. A visit to this pool June 4 found Ranatra 

 eggs abundant on top of floating dead Typha, some of them showing the 

 red eye spots. The photographs on plate VII are of some of these. 

 Pettit, 1902, gave some very good drawings of Ranatra eggs which he 

 described. 



Incubation. Latreille said, "lis restent quinze jours au fond de I'eau." 

 Kulgatz says R. linearis is in egg stage two weeks. Bueno gives two or 

 three weeks for the incubation period. In one aquarium the writer found 

 eggs deposited on May 11 hatched June 14. This was at Ithaca, N. Y. 



Hatching. Bueno says the young emerge through a round cap at the 

 top, which bears the filaments. Brocher gives a similar brief account. In 

 hatching the nymph casts a clear membrane, post-natal molt, which it 

 leaves as a diaphanous mantle, crumpled into a shapeless mass, and 

 clinging at its caudal end in the fissure of the shell. See plate XVIII. No 

 hatching "burster" is discernible under high power binoculars. Holmes 

 1907, says "When one sees a Ranatra on emergence from the egg he can- 

 not but be surprised that the young insect should have been inclosed in so 

 small a receptacle. The body of the nymph is as broad as the egg and 

 over twice as long." 



Number of Instars. There are five nymphal instars. Bueno reared 

 one to the adult stage and found that the first instar lasted 8 to 14 days; 

 the second 9 days; the third instar 7 days; the fourth instar 8 days; the 

 fifth instar 8 days. "A total of 61 days from egg to adult." 



Fecundity. The writer believes that these bugs produce many eggs, 

 because in one restricted pool where there were few Ranatra the eggs 

 were very abundant. 



Food Habits. Here there is a long list of references dating to an early 

 time. The food of the young, says Holmes, "consists chiefly of small 



