Oct. 22, 1921 Hopkins Host-Selection Principle 203 



CONCIvUSIONS 



This crossing of the two host forms had no influence on the selection of 

 hosts. 



The amount of wood and number of adults present influence the host 

 selection, as shown when one female and two females were given the same 

 amount of wood. 



CYI,I,SNE CRINICORNIS. BXPERIMENT XI,I 



Cyllene crinicornis Che v., found in the southwestern United States, is 

 known to feed only in mesquite (Prosopis juliflora (Swartz) de C.) and 

 occasionally on an allied legume, paloverde {Parkinsonia microphylla 

 Torr.). In general its biology is similar to that of C. pictus, and it pre- 

 fers the same conditions of wood. Adults begin emerging in the natu- 

 ral range during late February, and part of this generation emerges in 

 September. 



Mesquite infested with these larvae was sent to Falls Church, Va., by 

 T. E. Snyder from San Antonio, Tex., April 27, 191 7. Adults emerged 

 at Falls Church the following May and were caged on mesquite cut in 

 March, 1918. A good infestation was secured and has since been con- 

 tinued on mesquite. 



RoBiNiA. Experiment XLr. — In May, 19 18, two pairs were isolated 

 on locust cut February, 19 18. May 31 the females were dead, and the 

 abdomens were dissected and found to contain eggs. Probably no eggs 

 were laid, and in July no evidence of larval work could be found. 



July 24, 19 1 8, seven nearly matured larvae were transferred from the 

 mesquite to locust cut January, 1918. During May, 1919, five adults 

 emerged. One pair was caged on locust cut in January, 1919, and one 

 pair on both locust and mesquite. The mesquite was cut October, 19 18. 



July 16, 1919, these cages were examined, and the selection test showed 

 that mesquite was not infested, whereas the locust contained several 

 small larvae. The cage containing only locust was lightly infested. 

 None of these larvae transformed in 1920. 



CONCLUSIONS 



The locust was such an unfavorable host that the adults would not 

 oviposit on it, but larvae may live and transform for one or two genera- 

 tions when forced to take it. 



CALUDIUM ANTENNATUM. EXPERIMENT IV 



Some confusion exists as to the taxonomy of the blue species of Calli- 

 dium allied to Callidium antennatum. A number of species have been 

 described of questionable validity. Two species have been experi- 

 mented with — C. antennatum and C janthinum Lee. These two adults 

 are easily separable, and their habits are also quite distinct. The 



