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 by four beetles. 
Number of specimen. 
Comple- 
tion of 
pupal 
chamber. 
Pupa- 
tion. 
Trans- 
forma- 
tion. 
Emer- 
gence. 
j 
July 15 
do 
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, prothorax, 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 slowly 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 fist 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 
