Februakt 7, 1908] 



SCIENCE 



225 



their preservation and authenticity guaran- 

 teed. 



Plate 16, Fig. 9, represents L. tortusa 

 Tower, a " variety " of decem-lineata; it ap- 

 pears to be a sport such as is sometimes pro- 

 duced by malformation or slight injury to the 

 pupa. Such oddities of color-pattern, and 

 much more striking ones, produced in such 

 manner, are of frequent occurrence in the 

 Coccinellidse. 



The statements regarding the distribution 

 of Leptinotarsa on page 3 are at variance 

 with those in the table on page 1. 



But it is when we come to the discussion 

 of L. decem-lineata^ and the book may almost 

 be said to be a treatise on this one species, that 

 the superficiality of the author becomes most 

 apparent. L. muliitceniata, which occupies 

 central Mexico, is stated to have extended its 

 range to the northward along with its food 

 plant, Solanum rostratum, in the wake of 

 the Spanish conquerors in their progress 

 northward. In its new habitat (northern 

 Mexico and Texas) it was transformed into 

 the form "intermedia." The introduction 

 and dispersal of Solanum, rostratum into 

 northern Mexico along the lines of early 

 Spanish travel, and its spread from there 

 farther north by the bison, are discussed at 

 great length. L. intermedia of northern Mex- 

 ico, after it reached the eastern slopes of our 

 Eockies, was transformed into decem-lineata. 



The whole argument turns upon the hy- 

 pothetical dispersal of Solanum rostratum 

 and the assumption that this plant is the orig- 

 inal food plant of L. decem-lineata. We are 

 virtually asked to believe that since the days 

 of the Spanish conquest L. muliitceniata has 

 produced the two species intermedia and 

 decem-lineata. Professor Cockerell has made 

 the claim that in New Mexico Solanum eleag- 

 nifolium is the normal food plant of L. decem- 

 lineata. As Dr. Chittenden has pointed out 

 to me, the species of Leptinotarsa will feed 

 upon various species of Solanum^ preferring 

 the more succulent ones. 



On page 24 we learn that " the original dis- 

 tribution of decem-lineata was on the eastern 

 slope of the Eocky Mountains northward to 

 the Canadian boundary, eastward into western 



Kansas and Nebraska, and southward into 

 Texas and New Mexico. In this habitat it 

 was found by Say in 1823. Then, as now, it 

 was probably sparsely distributed over the 

 area, feeding upon Solanum rostratum." It 

 would be interesting to know from what 

 sources Professor Tower obtained all this in- 

 formation regarding the original habitat and 

 food plant of the species. After the original 

 description of the species by Say, we find the 

 remark : " This species seems to be not un- 

 common on the Upper Missouri, where it was 

 obtained by Mr. Nuttall and by myself. The 

 variety' I found on the Arkansas." The 

 variety in question, in which " the two outer 

 intermediate lines are united at base and tip " 

 is undoubtedly L. juncta; therefore the orig- 

 inal habitat record is from the upper Missouri 

 only, and certainly very little was added to 

 our knowledge of the beetle until the time 

 when it became of economic interest. 



The eastward spread of the beetle and the 

 factors that controlled it are presented in 

 detail. Beginning with p. 44, the effect of the 

 wind on the dispersal of L. decem-lineata dur- 

 ing its progress eastward is discussed. On 

 page 47 it is stated that the prevailing south- 

 erly winds greatly retarded the southward 

 progress of the beetle. The scarcity of its 

 favorite food plant in the south is much more 

 likely to have been a barrier to its progress. 

 The facilities for dispersal offered by the boat 

 traific on the Mississippi and its tributaries 

 (see p. 30) would more than offset the influ- 

 ence of the unfavorable prevailing winds. 



Tower states that the species of Leptino- 

 tarsa are double-brooded. This point, it seems 

 to me, needs further investigation. My own 

 experience with species of many genera of 

 Chrysomelidse has shown that they are all 

 single-brooded and that the newly developed 

 beetles do not become sexually mature until 

 the following season. I have had no experi- 

 ence with Leptinotarsa, 'hv± abundant data 

 which show that such closely related genera 

 as Galligrapha, Lina.and Gastroidea are only 

 single-brooded. Such a physiological differ- 

 ence in alternating generations, of quick sex- 

 ual maturity in one brood and of a long period 

 of sexual inactivity in the other, would be 



