TETKAMEROUS PLANT-BEETLES. 



165 



A. Last joint of palpi -widened and truncated ; claws toothed Orsodacna. 



A A. Last joint of palpi not wider than the others and pointed ; claws simple Crioceris. 



Orsodacna, a name taken from the Greek and meaning a hud-gnawer, 

 was originally applied to some insect now unknown, which was injuri- 

 ous to fruit trees. It includes three Sub-genera: Orsodacna, Latr., having 

 the thorax uniform and the eyes entire ; Zeugophora, Kuuze, having the 

 eyes notched and the thorax with a lateral tubercle ; and Syneta, Esch., 

 with several short teeth at the sides of the thorax. The species are of 

 moderate size, and either blackish or dull yellow, but more commonly 

 with both of these colors combined. We have twelve species, some of 

 which are very variable, and have been described under different names. 

 The only species of Crioceris proper found in the United States, is the 

 imported asjjaragus beetle, Crioceris asparagi, Linn., which has become 

 naturalized in some of the Eastern States. Most of our species are now 

 placed in the sub-genus Lema, Fabr., as restricted by Lacordaire, and 

 distinguished by having the thorax constricted or narrowed a little be- 

 hind the hiiddle. The most common species is the Lema trilineata, Oli- 

 vier, or the Three-lined potato-beetle, a quarter of an inch long, yellow, 

 with three black stripes on the elytra. Mr. Crotch enumerates twelve 

 other species, most of which inhabit the Southern States. 



Sub-family CHRTSOMELIDES. 



This sub-family is founded upon the typical genus Clirysomela, of Lin- 

 naeus, a word which literally means a golden apple, and which was ob- 

 viously given to these insects in allusion to their rounded form and 

 [Mg. 81.J beautiful colors, which not un- 



frequently exhibit a golden hue. 

 Their most distinctive scientiJic 

 character, as comi^ared with the 

 other sub-families of this tribe, 

 is the distance from each other 

 of the antennae at their points of 

 attachment, being always farther 

 apart than the length of the first 

 ^nt'erior^ilf-joiut, and often two or three 

 times as far, taken in connection 

 with the gradual but slight enlargement of these organs towards the 

 tip. The sub-family comprises two well-marked groups, which are re- 

 garded by some entomologists as distinct sub-families, and which may 

 be designated by the terms of Chrysomelini and Eumolpiiii. In the 

 former the thorax is transversal, that is, wider than it is long, strongly 

 margined, and as wide at base as the elytra; the antenna? are moder- 

 ately robust, sub-moniliform, and almost always less than half as long- 

 as the body ; the anterior coxse are transverse; the 3d joint of the tarsi 



Chrysomela (myocortna) juncta, German 

 h 6, larvse ; c, beetle ; d, wing-cover 

 after Riley. 



