26 BULLETIN OF THE BUREAU OF FISHERIES. 



the adult beetle. These spiracles open to the exterior through the pupa case, and 

 hence the pupa not only breathes through them but if it is submerged under water 

 it drowns, having no provision for keeping them covered with a film of air like the 

 adult beetle. (See p. 30.) 



The length of time spent in the pupal chamber varies considerably, but averages 

 from two and a half to three weeks. This period is divided as follows: From 5 to 

 8 days are passed by the larva after the pupal chamber is completed and before 

 pupation; from 7 to 12 days are passed in the pupa state; and 4 or 5 days are spent 

 by the adult beetle after transformation before it emerges. The table below gives 

 these periods for four beetles that were under observation continuously. 



Periods spent in pupal chambers hy four beetles. 



Number of specimen. 



Comple- 

 tion of 

 pupal 



cnamber. 



Pupa- 

 tion. 



Trans- 

 forma- 

 tion. 



Emer- 

 gence. 



1 



July 15 



July 20 

 July 23 

 July 22 

 July 23 



July 27 

 Aug. 3 

 Aug. 2 

 Aug. 4 



July 31 

 Aug. 7 

 Aug. 6 

 Aug. 9 



2 



3 



July 16 



4 







THE ADULT BEETLE. 



A pupa was dug up on July 27 that was just ready to transform, and the adult 

 beetle crawled slowly out of the pupa case while being watched. At the instant 

 of transformation the entire body was white, but in the sunlight to which it was 

 exposed the head, pro thorax, scutellum, and legs became a rich mahogany red 

 even before it had entirely gotten out of the pupa case. The elytra became light 

 salmon pink; the wings and abdomen remained white. The color first appears on 

 the wings as a faint salmon pink along the ribs and veins, which gradually deepen 

 to a reddish-brown. The web of the wing slowly loses its bleached-white aspect, 

 but remains colorless, of course, even in the matured adult. 



The elytra stretch to their full size almost instantly on being set free from their 

 pads, and in the course of an hour become dark reddish-brown. The abdomen 

 remains white longer than any other portion of the body — several hours, in fact — 

 then gradually turns reddish-brown. The color appears first on the ventral sur- 

 face along the central carina and the sutures between the segments, and gradually 

 spreads in all directions. On the dorsal surface the last and smallest segment is 

 colored first, then a faint line appears along the center, which §lowly spreads out- 

 ward on either side. The beetle above mentioned came out of the pupa case about 

 10 a. m., and by the next morning it was entirely black on the upper surface, while 

 the under surface still remained a dark mahogany brown. 



This rapid change of color was not due wholly to the influence of the sunlight, 

 for the first beetle on the list just given, which transformed during the night of 

 July 27, was entirely black on the upper surface the next morning, and it had 

 remained in the darkness of the pupal chamber all the while. The fourth beetle 

 on the list was taken out of its pupal chamber several times, but would not remain 

 in the light and returned to the chamber. On August 9 it came out voluntarily 



