THE COLORADO POTATO BEETLE. 



elytra. The pronotum of L. obsoleta has reddish margins 

 enclosing a rounded, black spot, or is reddish with 3 or 4 

 black spots at the center; elytra purplish-black with the 

 margins, tips, and often two short, indistinct lines on basal 

 half, reddish-yellow. 



The third tarsal joint of the following genera of this 

 tribe is not, or scarcely, indented ; the pronotum has a thin 

 margin at the base; the insects are usually more than .25 

 in. long, robust, and convex. 



Labioderma clivicollis feeds on milkweed. It is dark 

 blackish-blue; elytra orange-yellow with variable, broad, 

 curved, black markings; mesosternum prominent, forming 

 a blunt tubercle between the middle coxae; front femora of 

 male strongly toothed. 



Leptinotarsa has simple femora and the mesostcrnum is 

 not raised above the level of the prosternum. L, decem- 

 iineaia, the Colorado Potato Beetle (Plate LXXXIII), is 

 probably the most known Coleopteron in America. The 

 elytral punctures are confluent and in double rows. Until 

 about 1855 it was confined to the Rocky Mountain region 

 where it fed on the w T ild relatives of the potato. Then 

 man introduced potatoes to it, and it did the rest, spreading 

 over the entire East. Adults hibernate underground. 

 Each female lays about 500 eggs and there are two genera- 

 tions a year. In the South there is another species, 

 juncta, which is somewhat similar but the third and fourth 

 black bands on each elytron are usually united at the 

 base and apex; the elytral punctures are regular and in 

 single rows. 



In Zygogramma the tarsal claws are parallel and united 

 at the bases; claw-joint toothed beneath. The adults of 

 suturalis, which occur on ragweed in the spring and ori 

 golden-rod in the fall, are brown, feebly bronzed; elytra 

 yellow with dark brown stripes, or vice versa. 



The elytra of our Chrysomela are without spots and the 

 sides of the pronotum are thickened. Like Calligrapha, 

 the last palpal joint is not shorter than the next to last. 



The elytra of Calligrapha have dark markings and the 

 sides of the pronotum are not thickened. To mention a 

 few of the many variable species, first taking those with 

 yellow and brown stripes on the elytra: lunata (chiefly on 



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