190 Journal New York Entomological Society. [Voi. xv. 



Class I, HEXAPODA. 

 Order II, COLEOPTERA. 



NOTES ON LEPTINOTARSA UNDECIMLINEATA 



STAL. 



By Frederick Knab. 

 Washington, D. C. 



The chrysomelid beetle Leptinotarsa undecimlineata Stal was found 

 by the writer in great abundance on the 17th of June, 1905, at Car- 

 men and at other points in the state of Vera Cruz, Mexico, along the 

 railroad running southeastward from Cordoba to Santa Lucrecia on the 

 Isthmus of Tehuantepec. The insects were feeding upon Solanum 

 torvum L., and had evidently been stimulated to sexual activity by the 

 first rains of the wet season. Many pairs were found in copula and 

 one cluster of eggs was found, placed on the underside of a leaf as in 

 our L. decemlineata. These eggs of L. undechnlineata are of an ex- 

 tremely pale yellow, in remarkable contrast with the deep golden yel- 

 low, almost orange color of the eggs of Z. decemlineata. There were 

 no larvae at this time. 



The females are remarkable in the enormously distended abdomen, 

 a condition supposedly peculiar and characteristic in certain genera of 

 Chrysomelidae. In these females of L. iindeci7nlineata the abdomen 

 is swollen to such a degree that it is not only exposed at the sides and 

 between the widely divergent elytra, but a large portion of it protrudes 

 beyond the tips of the elytra. The fourth and succeeding segments 

 project beyond the elytra in a specimen preserved in fluid, taken by 

 Mr. B. Jordan in Alta Vera Paz, Guatemala. On the exposed abdo- 

 men the dorsal plates appear as narrow black transverse strips upon 

 the broad white area of the expanded connecting tissue. This condi- 

 tion of the female is even indicated in dried specimens where the ely- 

 tra have come together over the shrunken abdomen ; the sutural 

 margins of the elytra show a slight divergence towards the tip. In the 

 genus Gastroidea, noted for the greatly swollen abdomen of the fertile 

 female, there is a modification of the abdominal integument. In some 

 females of G. cyanea examined by the writer the entire integument of 

 the abdomen is uniformly pigmented and apparently of the same 

 texture throughout. 



