242 THE CANADIAN ENTOMOLOGIST. 



LIFE HISTORIES OF NORTH AMERICAN WATER-BUGS. 



BY J. R. DE LA TORRE BUENO, NEW YORK. 



II. 



Life-History of Ra?tat?-a quadridefiiata, Stal. 



Of the water-bugs, perhaps Raiiatra and Nepa are better known than 

 the others in their anatomy and earh'er stages. Dufour's classic on the 

 anatomy of Nepa ci/ierea, L., and Fanatra linearis^ L., has been followed 

 by the work of other investigators in these two species, and the peculiar 

 filamentous ova of the two genera have long been favourites with students. 

 But nevertheless, thus far no complete life-history has been worked out 

 for either of them. In the following pages are presented the results of 

 my preliminary breedings of Ratiatra quadridaitata, Stal. 



The remarkable eggs of Rafiatra have received much attention from 

 European entomologists, and the use of the two filaments adorning them 

 has been the subject of much speculation. They are deposited in the 

 early spring in the decaying stems of rushes, and in the course of three 

 weeks or so the little bugs emerge. They very much resemble the adult, 

 except that they are, of course, much smaller. After five moults, they 

 reach maturity in some eight weeks or so. It is possible that there may 

 be two broods from ova deposited early in May, but there are no data 

 bearing on this point, although I have taken young nymphs as late as 

 September. In copulation, the male is below and to one side of the 

 female. The adult female is furnished with a pointed, keeled, toothed 

 ovipositor, and can be readily distinguished from the male, in which the 

 ventral portion of the genital segment corresponding to the ovipositor is 

 not keeled, is flatter, and more rounded at the extremity.^ 



Ranatra quadridentata frequents deep waters, where it clings quite 

 fast to the stems of rushes or grasses, with its air-tube or siphon piercing 

 the surface film. At times it swims about, while at others it simply floats 

 head down, with the tip of its air-tube at the surface. It will also float 

 parallel to the surface of the water, at a greater or less distance from it, 

 and in such cases the air-tube makes an angle with the body, varying in 

 sharpness according to the depth at which the bug lies. One Ranatra 

 was taken perched on a lily-pad, the tip of the siphon touching its surface, 

 and the legs straight and inclined backwards. This is much the position 

 it assumes on taking flight. After balancing itself a moment in this 

 posture, the bug crouches far back, with its legs much bent, and then 

 suddenly leaps into the air with a loud whirring noise made by its wings. 



]. ex. Uhler in Standard Natural History, Vol. II, p. 253. 

 July, 1906 



