GUIDE TO THE STUDY OF BRITISH WATERBUGS. 233 



described, has been mentioned by Motschulsky as being utilized 

 for similar purposes. I have discussed this at some length, and 

 have also figured an egg of .1. mercenaria.*- 



The nymphal stages are not specially remarkable. De Geer 

 (tom. 3, pi. 20, figs. 16 and 17) figures some, but modern de- 

 tailed figures are needed. The metamorphosis of the Corixidae 

 takes some three months or so, or perhaps less ; the species all 

 hybernate in the adult stage except (according to F. B. White) 

 those of Micronecta. 



The CorixidaG have a distinctly ''buggy" smell — and taste ! 

 Dufour says that they are carnasial : I think that small worms, 

 Rotifera, &c., form a large part of their food. The internal 

 anatomy is described by Dufour, also by Burmeister (1835, 

 Handb. der Entom. ii. 186), iox punctata (i.e. geoffroyi). 



The Corixidse breathe in a peculiar manner, which has been 

 well described f by A. S. Packard, whose recent death everyone 

 will deplore. The Corixid "takes in the air so suddenly that it 

 is impossible without long and patient observation to see the 

 mode, which we have been unable to find described. It rises to 

 the surface in a horizontal position, and no sooner is the surface 

 reached than it darts to the bottom, and in one instance remained 

 there for ten minutes by the watch, and then darted up again, 

 leaving an air bubble in its wake, which rose to the top after- 

 wards. It carries down with it a broad silvery streak along the 

 side of the body. The air is really introduced under the head 

 and front thorax. The head is large and very movable, as well 

 as the prothorax. It slides back and forth on a thin membrane, 

 from the surface of which it can be raised. So with the hinder 

 edge of the prothorax, which rides over the membranous hind 

 thorax, which it nearly conceals. When the Corixa rises to the 

 surface it floats in a horizontal position, the hind edge of the 

 head and the prothorax rising slightly above the surface. Now 

 slightly raising the back of the head and the hind edge of the 

 prothorax, a space appears in front of and behind the prothorax, 

 by which the air passes into the breathing-holes beneath. This 

 is proved by the small bubbles of air remaining in these two 

 cracks. Two minute spiracles may be detected in deep pits, one 

 on each side, just above the insertion of the legs, and from which 

 the tracheae arise, each one dividing into three irregular short 

 branches, as may be seen by detaching the segment and holding 

 it up to the light." 



Corixidse are often used as hosts by Hydrachnid larvae, which 

 are attached as in the Naucoridae. Ouchakoff describes, but 



•'= See " An Economic Use for Waterbugs " in Ent. Mo. Mag. (2) ix, 

 173-5 (1898), and " Sur quelques hemipteres aquatiqnes nouveaux ou peu 

 connus" in Revue d'Entom. 1899, p. 95, and fig. 6. 



f " Half-hour Recreations in Natural Historj' — Half-hours with Insects," 

 p. 141. 



ENTOM. — SEPTEMBER, 1905. U 



