152 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



brilliant green coloration of their parents and they are then act- 

 ive and intent upon reproduction. Dr. Dimmock and the 

 writer have corroborated Caulfield's observations by rearing 

 the beetles from the eggs and carrying them through to the 

 following season. 



Transformations of a similar character have been observed 

 in certain species of European Cassidini, but their correlation 

 with the physiological changes of the reproductive period ap- 

 pears never to have been suspected. A much less obvious case 

 is that of another American cassidid, Chelymorpha argus Lich- 

 tenstein. This beetle at first, shows an ochreous yellow ground- 

 color above, and it is not until it issues from hibernation and 

 is ready to reproduce that it shows the characteristic dull 

 red ground-color. Incidentally it may be mentioned that at 

 Winnipeg, Manitoba, the writer found a race of Chelymorpha 

 argus which is ochreous yellow when sexually mature. 



Similar changes occur in certain Chrysomelini when sexual 

 maturity is acquired. A striking case is that of Zygogramma 

 signatipennis Stal, which the writer found abundant upon a 

 large composite plant at Cordoba, Mexico. During the winter 

 months the beetles could be found but sparingly upon their 

 food-plant and appeared to be very inactive. At that time the 

 ground-color of the elytra was a dull creamy white. With the 

 advent of warm weather and the rains the beetles became 

 abundant ; they were now active and many pairs were observed 

 in copulation. The ground-color of the elytra had now changed 

 to bright green-gold. In certain of our native species of 

 Calligrapha the ground-color of the elytra is at first creamy 

 white, and this takes on a silvery luster when the beetle "becomes 

 sexually mature. In Calligrapha rhoda Knab the contrast is 

 enhanced by the addition of red to the elytral pattern with sex- 

 ual maturity ; this change takes place in a still more striking 

 manner in Calligrapha roivena Knab. As these beetles have 

 been described in a previous article it would be superfluous to 

 go into the details of coloration. 



Tower in his book on evolution in the genus Leptinotarsa,* 

 proposes names for certain Mexican forms of this genus 

 which he claims to be new. He states that these species show 

 colors in life which disappear after the death of the insect and 

 that these colors are of specific value. Doubtless in these cases 

 also the colors in question are correlated with the sexual 

 functions, for in all the cases previously cited, the nuptial colors 



*An Investigation of Evolution in Chrysomclid Beetles of the Genus 

 Leptinotarsa. (Pub. No. 48, Carnegie Institution of Washington, 1906.) 



