211 



l)low-saud and ordinary soil which further observation and ex- 

 periment may show to have a controllinj^ influence on the local 

 distribution of species, these factors do not, so far as our pres- 

 ent information goes, satisfactorily account for the observed 

 peculiarities of specific distribution. 



The Relation of Sand and Climate to Insect Colokation. 



One of the most evident color adaptations among sand in- 

 sects is that of direct imitation of the color effect of the sand. 

 The exposed condition of insects upon any surface where the 

 vegetation is more or less scanty makes it advantageous that 

 all species existing there and lacking other means of protec- 

 tion should be as inconspicuous as possible; and species on 

 our list belonging to various orders, have developed remarkably 

 pale dorsal colors, apparently for this reason. In the case of 

 the Carolina grasshopper {Dissostc/fn ciiroliHd), whicli inhaliits 

 not only the sand surfaces in this district but also the darker 

 bare .surfaces, individuals taken on the sand seemed to show a 

 decided approximation towards its color when compared with 

 those from darker ground in Champaign county. Vosseler, who 

 has studied out and described in detail the fundamental pattern 

 of the An-i(i;i(hr ('02, Bd. 17. p. 22), calls attention to the fact 

 that the molting occurs in daylight, and that the nearly col- 

 orless fresh exterior is then exposed to the action of reflected 

 rays from surrounding surfaces, which, he suggests, may in 

 some way, by photographic action, produce an approximation 

 to their general color. How this can occur is not clear, but 

 Poulton's experiments on Lfpidoptera, and various other obser- 

 vations, all point to some such effect. The observations con- 

 cerning the Carolina grasshoppers above recorded (made before 

 reading Vosseler's paper ), and the great differences in the ground 

 color of individuals of this species can be satisfactorily account- 

 ed for only in this way. 



The more evident examples of sand imitation are the pale 

 brown of Hdritahis tcsfdccus, II. crrdficiis, and (Jeojnuns tticfds.sa- 

 tns, the broad white markings of Cicindela lepida and Tetru- 

 r/onodfiriis fusriafiis.the ashy grays of Stiirlui<„-iiciiiis and Eiuhle- 



