Dec, 1907.] Knab : Leptinotarsa undecimlineata. 191 



The coloration of Leptinotaisa undecimlineata is noteworthy. 

 While dried specimens differ but little in this respect from L. decem- 

 lineata, the ground color of the elytra and thorax of the live specimens 

 is a peculiar very pale greenish gray, and this in the breeding season 

 when the colors should be at their fullest and no immature individuals 

 present. 



Dr. E. Duges has given a detailed description, accompanied by 

 figures, of the early stages of this beetle.* He describes the larva as 

 white in color with black markings. The markings are very different 

 from those of our Z. decemlineata and the species related to it. The 

 head, legs and prothoracic shield are black. The meso- and meta- 

 thorax bear small black lunar marks at the sides. Segments 1-6 of 

 the abdomen have heavy black lunar marks at the sides which involve 

 the stigmata ; on segments 1-5 the ends of the opposing lunules are 

 connected by slender, more or less broken, dorsal lines. Segments 

 6, 7 and 8 bear quadrate black dorsal areas. These markings vary 

 greatly in amount and all intergrades occur to a form in which only 

 round black stigmatal spots are present. This is the form figured by 

 W. L. Tower, f The pupa is white with only the stigmata black. 



The food plant is large and spiny with coarsely hairy leaves. Dr. 

 Duges gives its name as Solanum tarduin but as no species of that 

 name is known the above mentioned Solanum torvum is doubtless 

 intended. 



Duges has found many of the larvae, particularly the young ones, 

 more or less covered with the hairs from the leaves of the food-plant. 

 As these hairs are attached very irregularly and are absent in many 

 larvae he assumes they adhere accidentally during the movements of 

 the larva in feeding and are not adopted as a defensive covering. 

 Tower describes this condition in the following words : "As the small 

 larvae push about through the abundant trichomes on the leaves of 

 their food plants, a large accumulation of these become lodged among 

 and cemented to the spines by the secretion of the dermal glands, 

 until the larva presents the color and appearance of a ball of dislodged 

 trichomes. . . . The integument in this second stage is smooth and 

 entirely devoid of spines on the tergal and sternal elements of the seg- 



*Ann. Soc. Ent. Belg., Vol. XXVIII, pp. 1-6, PI. I, 1884; Spanish transla- 

 tion: La Naturaleza, Vol. VII, pp. 308-311, PI. VIII, 1887. 



f An investigation of evolution in chrysomelid beetles of the genus Leptinotarsa, 

 1907, pi. 17, figs. I, 2 and 3. 



I 



