THE BIOLOGY OF THE ALDER FLEA- BEETLE. 267 



(1887) corrected this statement, suggesting that Packard's des- 

 cription might have been made from an alcoholic specimen, or 

 that just formed pupae might possibly be white. The context 

 precludes the former explanation, and as has just been stated, 

 the newly formed pupae, like the older ones, are yellow. Essig 

 (1915) stated that the pupae are either white or yellow, but 

 this statement is probably incorrect. The writer has spoken of 

 this at length because bimarginata pupae may be distinguished 

 from certain other Altica pupae which are white, by the color 

 characters, which are very constant. As the pupae of bimarginata 

 do become white in alcohol, this distinction is useful only in the 

 case of living pupae. 



"Figure 27 shows the dorsal aspect of the pupa; figure 28, 

 the ventral aspect; figure 21 A, the arrangement of the setae, 

 dorsal aspect, (mesothorax, metathorax, abdominal segments I 

 through 8) ; figure 21 B. the arrangement of the setae, ventral 

 aspect; figure 21 C, the setae of the 8th abdominal segment and 

 the pygidium; figure 21 D, the setae of the prothorax, dorsal 

 aspect. 



Color changes of the pupa. As has been stated, the pupa 

 when formed is entirely bright orange yellow, except for the 

 brown setae and the black caudal spines and the spiracles, which 

 are also black. But as the pupa grows older, certain color 

 changes appear, which are correlated with the internal meta- 

 morphosis, and furnish a good indication as to the age of the 

 pupa. All other species of the Alticini and the Galerucini which 

 the writer has studied show similar external evidences of the 

 progress of the internal metamorphosis by the formation of 

 pigment in the cuticula. 



The first change is to be noticed in the eyes, which become 

 light brown on the 4th or 5th day after the pupal molt. On the 

 7th day, as a rule, the eyes are dark brown, the wings light gray, 

 and the tips of the mandibles red brown. On the 8th day, the 

 eyes are black, the distal tarsal segments black, and the femoro- 

 tibial joints black; the labrum, the tips of the mandibles, and the 

 palpi are brown ; and there are brown spots on the pronotum. 

 On the last day of pupal life, in addition to these markings, the 

 coxae and tibiae are black, and the head is brown between the 

 eyes. 



There is of course a considerable amount of individual 

 variation as to the time required for the appearance of these 



