MELOIDAE. 209 



of the hind tibiae frequently differing in size and form ; an- 

 terior and middle tarsi 5-jointed ; hind tarsi 4-jointed ; penul- 

 timate joint almost always cylindrical ; claws usually divided 

 at the base, with the inferior portion very slender ; rarely not 

 divided, and then armed with a large tooth. 



This family contains species of moderate or large size found on 

 plants ; they are mostly of a soft consistence, and are remarkable 

 for secreting a peculiar principle, cantharidine, from which they 

 derive the blistering power, which causes them to be used in 

 medicine. 



They are equally remarkable in the development of the larva, 

 which assumes successively several forms, in the first of which it is 

 a very small active Pediculus-like parasite infesting bees of differ- 

 ent genera. 



Two tribes, first properly recognized by Lacordaire are thus 

 separated. 



Side pieces of nieso- and metatliorax covered by the elytra. Meloini. 



Side pieces of meso- and nietathorax visible. Lyttini. 



Tribe I.— MELOIJVI. 



The insects composing this tribe are without wings ; the elytra 

 are frequently much shorter than the abdomen, and in one genus 

 are imbricated, or overlap at the suture ; the metasternum is very 

 short, so that, except in Henous, the middle coxae extend partly 

 over the hind coxa? ; the side pieces of the meso- and metatliorax 

 are entirely covered by the elytra ; the claws are sometimes armed 

 with a tooth, sometimes cleft to the base ; in this case the upper 

 portion is never pectinate, as in certain genera of the next tribe. 

 The frontal suture is distinct, and the front is prolonged before 

 the insertion of the antenna?. 



Our genera are : — 

 Elytra short, imbricated; claws cleft. Meloe. 



Elytra not imbricated ; claws armed with a tooth ; 



Elytra much shorter than the abdomen, diverging. Megetka. 



Elytra connate, larger than the abdomen. Cysteodemus. 



Elytra subconnate ; claws cleft. Henous. 



Meloe is generally diffused, and is the only genus represented 

 on the Eastern Continent ; Henous is found from Kansas to Texas ; 

 Cysteodemus in Arizona and Colorado Desert ; the genus Mege- 

 tra Lee. (Arcana naturae, 1,127) is founded upon Meloe cancel- 

 latus Er., and Cysteodemus villatus Lee, which occur in New 



