530 ANIMAL SUBSTANCES 



CANTHARIDES 



(Spanish Flies, Cantharis) 



Source, &C. Cantharides are the dried beetles, Cantharis vesicaloria, 

 Latreille (Lytta vesicatoria, Linne, Phylum Arthropoda, Class Insecta, 

 Order Coleoptera). 



Cantharides, or, as they are frequently termed, Spanish flies, are 

 widely distributed over southern Europe ; they are gregarious and 

 inhabit chiefly ash trees, privets, elders, &c. They are collected in the 

 very early morning before sunrise (whilst they are unable to use their 

 wings) by shaking them from the trees on to cloths placed beneath ; 

 they are killed by exposing them to the fumes of ammonia, acetic 

 acid, or burning sulphur, or by stove heat ; they 

 are then dried, preferably by stove heat. When 

 fresh they possess a powerful, disagreeable odour, 

 which diminishes by keeping. 



They are collected in southern Russia, Galicia, 

 Roumania, and also to a much smaller extent in 

 Italy and Spain. 



Description. Cantharides are about 20 to 25 mm. 

 long, about 7 mm. broad, smooth, and of a shining 



FIG. 245.-Spanish green or c PP er y S reen colour - The wing-cases are 



blistering beetle, ^ on S an< ^ narrow, and conceal two transparent, 



Cantharis vesica- brown, membranous wings. Each insect possesses 



toria. Slightly en- three pairs of legs and one pair of antennae. 



Constituents. The principal constituent of can- 

 tharides is a definite crystalline body, cantharidin, 

 which, although almost insoluble in cold water and only sparingly 

 soluble in alcohol, dissolves readily in acetic ether, chloroform, and 

 benzene. With caustic alkalies (potassium or sodium hydroxide) it 

 unites to form soluble salts, and there is evidence to show that in 

 the beetles it exists partly as free cantharidin, partly in the form 

 of salts soluble in water. The soft parts of the insect are the chief 

 seat of cantharidin. Good Cantharides contain from 0-5 to 0-8 per 

 cent, or occasionally as much as 1 per cent. 



In addition to this substance the beetles contain about 12 per cent, 

 of fixed oil. 



Assay. Moisten 20 gm. of finely powdered Cantharides with 3 c.c, of hydro- 

 chloric acid, transfer to a Soxhlet apparatus and exhaust with benzene. Distil 

 off the benzene and boil the residual fatty matter for 10 minutes with 100 c.c. 

 of water acidified with hydrochloric acid, using a reflux condenser. Transfer 

 the hot aqueous solution to a capacious separator, and repeat the boiling with 

 four successive portions of 50 c.c. of water, unite the aqueous solutions, and 





