66 The Mechanism of Evolution in Leptinotarsa 



and between the type and variety (a) as described by Stal all kinds of inter- 

 grades occur. (Plate 7, fig. 3.) 



Size: Larger and more robust than L. decemlineata; sexes of nearly equal 

 size. Male, 11 to 16 mm. long, 8 to 11 mm. broad; female, 11 to 17.5 mm. long, 

 8 to 11.75 mm. broad. 



Sexes: Female with sternal sclerite of last abdominal segment rounded; 

 male with the same sclerite truncate and faintly grooved. 



Food: Mainly Solanum carolinensis. More rarely egg-plant or other succu- 

 lent or herbaceous Solanacese. Experience in cultures shows that S. carolinensis 

 is the only food upon which it thrives, and while it will eat other plants (S. escu- 

 lentum, 8. tuberosum), it in my experience does not thrive upon them, and can 

 not be reared for more than one or two generations thereon. 



Juvenile Stages. 



Eggs: Large, oval, rarely stalked, polished, smooth, pale yellow-pink in 

 color; 2 to 3 mm. long, 1 to 1.5 mm. broad; ventral flattening very slight. 

 Incubation, 7 to 12 days. 



First larval stage: Head, pronotum, and legs, black or dark brown; body, 

 pale bluish-pink, variable, spots variable, spiracula always present. Length at 

 end of stage, 3 to 4.5 mm. (Plate 7, fig. 9.) 



Second larval stage: Head, pronotum, legs, as above; but the dark color on 

 the pronotum is limited to the posterior edge and is variable ; body, pale bluish- 

 pink, spiracula spots only present. Length at end of stage, 5 to 7 mm. 



Third larval stage: Exactly like second (see Walsh, Am. Ent., I). Length 

 at end of stage, 10 to 16 mm. (plate 7, fig. 1). Length of larval life, 12 to 30 

 days ; average, 20 days. 



Pupa: Pupates in ground at depth of 1 to 5 inches. Pupa yellowish. Dura- 

 tion of pupation 10 to 25 days ; average, 14 days. 



Length of ontogeny, 30 to 60 days ; average, about 40 days. 



GEOQBAPHKJAIi DiSTBIBtJTION. 

 (Plate 3.) 



Irregularly and sparingly distributed over Atlantic Coastal Plain and nearby 

 areas. Not often common, and considerably restricted and reduced in numbers 

 and range since the advent of L. decemlineata. Does not extend southward into 

 Mexico, as far as has been discovered. 



Material for experimentation has come from the following locations : Atlanta, 

 Georgia; Mobile, Alabama; Lexington, Kentucky, and New Orleans, Louisiana. 



Geographical variety texana Sch. 

 (Plate 7, fig. 5.) 



Much confusion exists concerning this not uncommon form from Texas and 

 the Eio Grande Valley. It has been variously classed as L. dejecta Stal, as Say's 

 variety of decemlineata, while Townsend has described its larvae as those of 

 L. undecimlineata. 



I have reared it for many generations and find that it is genetically true and 

 constant to its type when grown side by side with L. juncta under the same 

 conditions and on the same food-plant — i. e., S. carolinensis. It differs from 

 L. juncta Guer. in a few minor attributes and these only in degree, not in kind. 

 I have, therefore, classed it as a geographic variety, it being comparable to the 

 other similar varieties here recognized. In that I have no means of knowing 



