OBSERVATIONS ON THE YOUNG OF RANATRA 

 QUADRIDENTATA STAL. 



S. J. HOLMES. 



In two previously published papers l I have described certain 

 features of the behavior of the water scorpion, Ranatra, and as 

 opportunity presented itself this last spring of obtaining young 

 Ranatras in abundance attention was devoted to a comparison of 

 the behavior of the young and the mature forms. The various 

 stages in the metamorphosis of the nymph were followed, but as 

 these have recently been described by Torre-Bueno 2 the obser- 

 vations made on this subject are omitted. 



Ranatra lays its eggs in the spring commonly in the stems of 

 aquatic plants or floating pieces of wood. The eggs are inserted 

 in the material containing them so that they are nearly buried. 

 They are of cylindrical form, rounded at either end, and provided 

 at the outer end with a pair of slender filaments of uncertain 

 function. When one sees a Ranatra which has recently emerged 

 from the egg he cannot but be surprised that the young insect 

 should have been enclosed in so small a receptacle. The body of 

 the young Ranatra is as broad as the egg and over twice as 

 long. The length of the young, measured from the end of the 

 proboscis to the tip of the breathing tube is frequently 8 mm., 

 while the egg itself is only about 3 mm. 



The young in general appearance closely resemble the adult 

 form. The prothorax, however, is relatively shorter, the wings 

 are entirely absent, and the breathing tube, or what functions as 

 such, 3 is relatively short, being about one fourth of the length of 

 the body, while in the adult it is about four fifths the length of 

 the body. At first the young are very soft. The slender legs 

 bend with the greatest ease, and if the insect is taken out of the 



'Holmes, "The Reactions of Ranatra to Light," Jour. Comparative Neurology 

 and Psychology, Vol. 15, p. 305. " Death Feigning in Ranatra," /. f., Vol. 16, p. 200. 



2 Torre-Bueno, Canadian Entomologist, Vol. 38, p. 242, 1906. 



3 Torre-Bueno, /. c., has shown that the so-called breathing tube of the young 

 nymph differs essentially in structure from that of the adult insect. 



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