449] COLORS OF TIGER BEETLES— SHELF ORD 55 



EXPERIMENTAL MODIFICATION OF COLOR 



This is frought by many difficulties on account of the remarkable 

 series of colors and color changes occurring in ontogeny, and the usual 

 early death of individuals reared under experimental conditions. Fig- 

 ure 555, plate XXIX, shows an experimentally modified individual 

 of C. lecontei. The presence of the yellowish color in the markings 

 indicates that secondary cuticula has been secreted with the air spaces 

 between, in quantity sufficient to give the opaque appearance to the 

 markings. This specimen in particular was known to have died 15 

 days after it was dug out of the soil, which is not until the cuticula 

 is well hardened. Its markings are reduced below anything ever 

 found near Chicago. The color shows an unusual amount of yellow 

 and approaches most nearly to some of the western forms of scutellaris 

 (Fig. 554) though not exactly like any forms known to occur. This 

 particular individual showed more yellow and was most generally modi- 

 fied, leaving no doubt as to the fact that color modification had oc- 

 curred. Three other individuals, all of which lived long enough to 

 show the development of opaqueness in the white markings, were pro- 

 duced and showed green of unusual clearness from reddish brown 

 and suggestive of green forms rather than the parent stock of lecontei. 

 All these were in dry conditions. The warm moist experiments showed 

 green forms but not clearly differentiated from ontogeny stages in part 

 due to early death. 



Three specimens (Fig. 557) were brought through successfully in 

 icing experiments and lived two weeks or more. Two of these were 

 characterized by broad markings and dull brown elytra and rather 

 striking differences between the color of the head and the thorax, the 

 latter being quite green. Figure 557 shows considerable modification 

 of form and size not noted in the other two. The very rounded ends 

 of the elytra, and square shouldered character was quite striking and 

 in direct opposition to the usual tendency shown in the rest of the 

 group. 



Figure 556 shows a specimen brought through at 37 °C. with 

 marked acceleration of development. This individual was small, slen- 

 der in the head and thoracic region, with the elytron widest in the 

 region behind the middle band. The color is much brighter and freer 

 from dull brown reflections than that of the normal specimens, having 

 a decided brilliancy to the color. This specimen was kept alive until 

 the opaque appearance of the markings was well developed. This body 

 form is characteristic of many specimens from the extreme southern 

 states. There is a noticeable general tendency toward this general 

 body form in all individuals reared in high temperature. 



