308 william lawrence tower. 



Competition Hybridization Experiments between 

 l. signaticollis and l. undecimlineata. 



L. undecimlineata X L. signaticollis. 



Exp. No. C. H. 47.3 Cuernavaca. 



In 1904, an isolated area of about an acre upon the southern 

 slope of a barranca, near Cuernavaca, was planted with food 

 plants, upon which both L. signaticollis and L. undecimlineata 

 would feed. In July, 1904, this spot was stocked with a culture 

 of 210 specimens of L. signaticollis, from a standard location about 

 a mile and half distant, and 354 specimens of L. undecimlineata, 

 obtained at El Hule, on the banks of the Rio Papaloapan. 

 Each of the groups was equally divided between the sexes, 

 were young and vigorous, immediately began breeding and inter- 

 crossed freely. Under experimental conditions these forms cross 

 freely in both directions, but out of them no new characters 

 come as the result of ordinary crossing. 



In the first generation of this colony there was an abundance 

 of individuals of both sexes of the signaticollis type, and of the 

 undecimlineata type, and of a highly variable intermediate hybrid 

 type. A census was made of the population on August 14 to 17, 

 with the following results : 



In this experiment, it was, of course, impossible to tell from 

 inspection whether the signaticollis individuals were pure signa- 

 ticollis, or pure signaticollis and a hybrid with the signaticollis 

 dominant, and the same was true with respect to the undecim- 

 lineata. All of the beetles entered into hibernation during the 

 latter part of August, and early September of 1904. The food 

 plants survived the long hard dry season and came up in the 

 spring of 1905 in abundance, and in June, 1905, individuals of 

 all three types emerged and were found to be interbreeding freely. 

 A census made of the individual which emerged late in June 

 gave the following results: 



