438 



ANIMAL DRUGS 



Epicauta vittata. The Old-fashioned Potato Beetle.* Found, 

 often abundantly, in the United States; feeds largely on leaves of 

 potato-plants. This insect was formerly official. 



Mylabris cichorii Fab., and M. phalerata Pallas. Chinese Blister 

 Beetles. Habitat: Southern and Eastern Asia. Cichorii has its 

 black wing-covers crossed by three broad orange-yellow bands; one 

 band is terminal, thus rendering the apices of the wing-covers yellow. 

 Mylabris bifasciata. The Two-striped Blister Beetle. Habitat: 

 Northern Africa. The body is black, the wing-covers presenting two 

 undulating narrow yellowish stripes. All these species of Mylabris 

 yield about i per cent, of cantharidin. 



ADULTERATION. Spanish flies exhausted of their vesicating principle have 



been met with as substitutions. Powdered 

 euphorbium has been spoken of as one of 

 the adulterants, but adulteration is not com- 

 mon in this drug. The assay of the drug is 

 accomplished by treating the powder with a 

 mixture of benzine (2 vols.) and petroleum 

 ether (i vol.), acidulated with HC1; digesting 

 the mixture; decanting the clear liquid, after 

 cooling; evaporating and purifying the residue. 

 For details, see U.S.P. IX. 



CONSTITUENTS. The chief constituents are: (i) 

 cantharidin, the active principle, a fatty 

 crystallizable body forming shiny, colorless 

 plates, soluble in alcohol, ether, acetic ether, 

 glacial acetic acid, chloroform, and oils; 

 volatilizable by heat (iooC., 2i2F.) with- 

 out decomposition, the vapor condensing in 

 acicular crystals; (2) a volatile oil, giving the odor of cantharides, 

 and said to have vesicatory properties; and (3) a green oil, the 

 coloring principle, closely allied to chlorophyll. 



Preparation of Cantharidin. Obtained by percolating the powder with chloro- 

 form, distilling off the liquid, and purifying the resulting crystals by washing them 

 with CSz to remove fat. Colorless prisms; soluble in alcohol, ether, fats, etc. 



Cantharidin is associated with certain alkalies and alkaline earths 

 in the drug, and seems to exist partly in combination with them. 

 The principle itself has been found to combine with salifiable bases 

 like an acid. 



ACTION AND USES. Internally cantharides acts as a powerful irritant, 

 and has a peculiar effect on the urinary and genital, organs. Large 

 doses produce violent strangury, attended with excruciating pain and 



This "Potato Beetle" should not be confused with the well-known Colorado Potato Beetle 

 (.Doryphora decemlineata. Say), belonging to the family Crysomelidse, a short, oval.^yellow-and-black 

 insect with ten longitudinal, stripes on its wing-covers. This latter beetle probably possesses no 

 vesicatory principle. 



FIG. 258. Old-fashioned 

 Potato Beetle (Lpicauta 

 vittata Fab.) (Origi- 

 nal. 





